Markdown linter (#1309)

* Add markdown linting

- add linter default rules
- adapt rules to current code
- fix the code for linting to pass
- add CI check

fix #1243

* Fix markdown for Substrate
* Fix tooling install
* Fix workflow
* Add documentation
* Remove trailing spaces
* Update .github/.markdownlint.yaml

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
* Fix mangled markdown/lists
* Fix captalization issues on known words

substrate/docs/Upgrade.md

@@ -1,5 +1,7 @@
-# Upgrade path for you building on substrate
+# Upgrade path for you building on Substrate
 
 ## master
- - crate rename has been fixed `sp-application-crypto` (was `sc-application-crypto`);  `.maintain/rename-crates-for-2.0.sh` has been updated accordingly, you can use it to upgrade to latest naming convention
- - crates have been renamed, run `bash .maintain/rename-crates-for-2.0.sh`
+ - crate rename has been fixed `sp-application-crypto` (was `sc-application-crypto`);
+   `.maintain/rename-crates-for-2.0.sh` has been updated accordingly, you can use it to upgrade to latest naming
+   convention
+ - crates have been renamed, run `bash .maintain/rename-crates-for-2.0.sh`