Markdown linter (#1309) (#2526)

* 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

(cherry picked from commit a30092ab42)

Co-authored-by: Chevdor <chevdor@users.noreply.github.com>

bridges/modules/parachains/README.md

@@ -19,7 +19,7 @@ validators. Validators validate the block and register the new parachain head in
 [`Heads` map](https://github.com/paritytech/polkadot/blob/88013730166ba90745ae7c9eb3e0c1be1513c7cc/runtime/parachains/src/paras/mod.rs#L645)
 of the [`paras`](https://github.com/paritytech/polkadot/tree/master/runtime/parachains/src/paras) pallet,
 deployed at the relay chain. Keep in mind that this pallet, deployed at a relay chain, is **NOT** a bridge pallet,
-even though the names are similar. 
+even though the names are similar.
 
 And what the bridge parachains pallet does, is simply verifying storage proofs of parachain heads within that
 `Heads` map. It does that using relay chain header, that has been previously imported by the