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/CODE_OF_CONDUCT.md

@@ -34,9 +34,9 @@ of preference.  We see that blockchains are naturally community platforms with u
 ultimate decision makers.  We assert that good software will maximise user agency by facilitate
 user-expression on the network. As such:
 
-- This project will strive to give users as much choice as is both reasonable and possible over what
+* This project will strive to give users as much choice as is both reasonable and possible over what
   protocol they adhere to; but
-- use of the project's technical forums, commenting systems, pull requests and issue trackers as a
+* use of the project's technical forums, commenting systems, pull requests and issue trackers as a
   means to express individual protocol preferences is forbidden.
 
 ## Our Responsibilities