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/frame/tips/README.md

@@ -11,7 +11,7 @@ entered where any remaining members can declare their tip amounts also. After th
 countdown period, the median of all declared tips is paid to the reported beneficiary, along with
 any finders fee, in case of a public (and bonded) original report.
 
-### Terminology
+## Terminology
 
 - **Tipping:** The process of gathering declarations of amounts to tip and taking the median amount
   to be transferred from the treasury to a beneficiary account.
@@ -30,4 +30,4 @@ any finders fee, in case of a public (and bonded) original report.
 - `tip_new` - Report an item worthy of a tip and declare a specific amount to tip.
 - `tip` - Declare or redeclare an amount to tip for a particular reason.
 - `close_tip` - Close and pay out a tip.
-- `slash_tip` - Remove and slash an already-open tip.
+- `slash_tip` - Remove and slash an already-open tip.