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/scheduler/README.md

@@ -23,12 +23,12 @@ then those filter will not be used when dispatching the schedule call.
 
 ### Dispatchable Functions
 
-* `schedule` - schedule a dispatch, which may be periodic, to occur at a
+- `schedule` - schedule a dispatch, which may be periodic, to occur at a
   specified block and with a specified priority.
-* `cancel` - cancel a scheduled dispatch, specified by block number and
+- `cancel` - cancel a scheduled dispatch, specified by block number and
   index.
-* `schedule_named` - augments the `schedule` interface with an additional
+- `schedule_named` - augments the `schedule` interface with an additional
   `Vec<u8>` parameter that can be used for identification.
-* `cancel_named` - the named complement to the cancel function.
+- `cancel_named` - the named complement to the cancel function.
 
 License: Apache 2.0