Subxt Guide (#890)

* WIP Starting to write book; extrinsics first pass done

* cargo fmt

* Ongoing work; events, constants, wip blocks

* at_latest() and wip blocks

* remove need to import parity-scale-codec crate with Subxt for macro to work

* More docs; expanding on setup guide and finish pass of main sections

* Tidy and remove example section for now

* format book lines to 100chars

* Fix example code

* cargo fmt

* cargo fmt

* fix example

* Fix typos

* fix broken doc links, pub mods

* Update Subxt macro docs

* can't link to Subxt here

* move macro docs to Subxt to make linking better and fix example code

* note on macro about docs

* cargo fmt

* document the no_default_derives macro feature

* Address feedback and remove redundant text

* address review comments; minor tweaks

* WIP add Runtime calls to book

* Improve Runtime API docs

* expose thing we forgot to expose and doc link fixes

subxt/src/config/mod.rs

@@ -29,7 +29,7 @@ pub trait Config: 'static {
     /// transactions associated with a sender account.
     type Index: Debug + Copy + DeserializeOwned + Into<u64>;
 
-    /// The output of the `Hashing` function.
+    /// The output of the `Hasher` function.
     type Hash: Debug
         + Copy
         + Send
@@ -95,7 +95,6 @@ pub trait Header: Sized + Encode {
 /// Take a type implementing [`Config`] (eg [`SubstrateConfig`]), and some type which describes the
 /// additional and extra parameters to pass to an extrinsic (see [`ExtrinsicParams`]),
 /// and returns a type implementing [`Config`] with those new [`ExtrinsicParams`].
-/// ```
 pub struct WithExtrinsicParams<T: Config, E: extrinsic_params::ExtrinsicParams<T::Index, T::Hash>> {
     _marker: std::marker::PhantomData<(T, E)>,
 }