docs: Extends #999. Remove disused package readmes. Rename to sr-metadata. Fix Readme Rustdoc names (#1016)

* docs: Remove safe-mix since is no longer local dependency

* docs: Fix existing packages link. Still only includes Substrate Core

* docs: Remove empty package Readmes. Remove old docs links. Rename to Readme

* docs: Remove link to old docs

* misc: Merge latest from master. Renaem to sr-metadata. Fix list of RustDoc package names

* Rename substrate-metadata to sr-metadata, since it is in the "srml" subdirectory

* Change example to use package name that opens all packages in RustDocs

* Fix list of packages names that are available to open in RustDocs

* fix typo

* fix ordering of CLI options and add missing backslash

substrate/core/test-runtime/README.adoc

@@ -1,13 +0,0 @@
-
-= Test runtime
-
-.Summary
-[source, toml]
-----
-include::Cargo.toml[lines=2..5]
-----
-
-.Description
-----
-include::src/lib.rs[tag=description]
-----

substrate/core/test-runtime/src/lib.rs

@@ -14,9 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
-// tag::description[]
 //! The Substrate runtime. This can be compiled with #[no_std], ready for Wasm.
-// end::description[]
 
 #![cfg_attr(not(feature = "std"), no_std)]
 

substrate/core/test-runtime/wasm/Cargo.lock

@@ -526,6 +526,16 @@ dependencies = [
  "sr-std 0.1.0",
 ]
 
+[[package]]
+name = "srml-metadata"
+version = "0.1.0"
+dependencies = [
+ "parity-codec 2.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec-derive 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "srml-support"
 version = "0.1.0"
@@ -538,7 +548,7 @@ dependencies = [
  "sr-io 0.1.0",
  "sr-primitives 0.1.0",
  "sr-std 0.1.0",
- "substrate-metadata 0.1.0",
+ "srml-metadata 0.1.0",
 ]
 
 [[package]]
@@ -551,16 +561,6 @@ name = "static_assertions"
 version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "substrate-metadata"
-version = "0.1.0"
-dependencies = [
- "parity-codec 2.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec-derive 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "substrate-primitives"
 version = "0.1.0"