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/client/state-db/README.md

@@ -2,15 +2,15 @@ State database maintenance. Handles canonicalization and pruning in the database
 this module is a `ChangeSet` which is basically a list of key-value pairs (trie nodes) that
 were added or deleted during block execution.
 
-# Canonicalization.
+# Canonicalization
 Canonicalization window tracks a tree of blocks identified by header hash. The in-memory
 overlay allows to get any node that was inserted in any of the blocks within the window.
 The tree is journaled to the backing database and rebuilt on startup.
 Canonicalization function selects one root from the top of the tree and discards all other roots and
 their subtrees.
 
-# Pruning.
+# Pruning
 See `RefWindow` for pruning algorithm details. `StateDb` prunes on each canonicalization until pruning
 constraints are satisfied.
 
-License: GPL-3.0-or-later WITH Classpath-exception-2.0
+License: GPL-3.0-or-later WITH Classpath-exception-2.0