Add subxt documentation (#546)

* Documentation for cli crate

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Add documentation and simplify calls generation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Add documentation and simplify events generation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Add documentation and simplify constants generation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Add documentation and simplify storage generation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Add lib documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* macro: Remove `-f bytes` as this is the default

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt/client: Add examples

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* lib_doc: Add documentation to dedicated file

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Link documentation from file

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Add more documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Add Storage example

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Add rpc documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* metadata: Add documentation for errors

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Add documentation for the `extrinsic` module

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Add documentation for `events` module

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Add `Static Metadata Validation` section

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Add `Runtime Updates` section

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Fix link to documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* readme: Remove hardcoded versions

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Move documentation to dedicated folder

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Spaces between examples

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* More details for `types_mod_ident`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Add note for RuntimeGenerator

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Address feedback

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update codegen/src/api/constants.rs

Co-authored-by: James Wilson <james@jsdw.me>

* Update subxt/src/lib.rs

Co-authored-by: James Wilson <james@jsdw.me>

* Update subxt/src/metadata/metadata_type.rs

Co-authored-by: James Wilson <james@jsdw.me>

* Update subxt/src/storage.rs

Co-authored-by: James Wilson <james@jsdw.me>

* Address feedback

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Fix cargo clippy

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update call example

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Add example for fetching constants

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Link to examples in subxt.md

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update codegen/src/api/calls.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update codegen/src/api/calls.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update codegen/src/api/calls.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update codegen/src/api/constants.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update codegen/src/api/constants.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update codegen/src/api/storage.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update codegen/src/api/storage.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update codegen/src/api/storage.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update docs/subxt.md

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update docs/subxt.md

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update docs/subxt.md

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update docs/subxt.md

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update docs/subxt.md

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update subxt/src/extrinsic/mod.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update subxt/src/storage.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

* Update documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update examples/examples/balance_transfer.rs

Co-authored-by: James Wilson <james@jsdw.me>

* Update subxt/src/extrinsic/mod.rs

Co-authored-by: James Wilson <james@jsdw.me>

* Update subxt/src/rpc.rs

Co-authored-by: James Wilson <james@jsdw.me>

* Update subxt/src/updates.rs

Co-authored-by: James Wilson <james@jsdw.me>

* Update docs example with `PolkadotExtrinsicParams`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Remove extrinsic extra documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Remove similar transfer example

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Apply cargo fmt

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

Co-authored-by: James Wilson <james@jsdw.me>
Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

subxt/src/rpc.rs

@@ -15,6 +15,49 @@
 // along with subxt.  If not, see <http://www.gnu.org/licenses/>.
 
 //! RPC types and client for interacting with a substrate node.
+//!
+//! This is used behind the scenes by various `subxt` APIs, but can
+//! also be used directly.
+//!
+//! # Examples
+//!
+//! ## Fetch Storage
+//!
+//! ```rust
+//! use subxt::rpc::Rpc;
+//! use subxt::storage::StorageKeyPrefix;
+//!
+//! // Storage prefix is `twox_128("System") ++ twox_128("ExtrinsicCount")`.
+//! let key = StorageKeyPrefix::new::<node_runtime::system::storage::ExtrinsicCount>()
+//!     .to_storage_key();
+//!
+//! // Obtain the RPC from a generated API
+//! let rpc: &Rpc<_> = api
+//!     .client
+//!     .rpc();
+//!
+//! let result = rpc.storage(&key, None)?;
+//! println!("Storage result: {:?}", result);
+//! ```
+//!
+//! ## Fetch Keys
+//!
+//! ```rust
+//! use subxt::rpc::Rpc;
+//! use subxt::storage::StorageKeyPrefix;
+//! let key = StorageKeyPrefix::new::<polkadot::xcm_pallet::storage::VersionNotifiers>();
+//!
+//! // Obtain the RPC from a generated API
+//! let rpc: &Rpc<_> = api
+//!     .client
+//!     .rpc();
+//! // Fetch up to 10 keys.
+//! let keys = rpc
+//!     .storage_keys_paged(Some(key), 10, None, None);
+//! for key in keys.iter() {
+//!     println!("Key: 0x{}", hex::encode(&key));
+//! }
+//! ```
 
 // jsonrpsee subscriptions are interminable.
 // Allows `while let status = subscription.next().await {}`