Update Identity pallet README.md according to the up-to-date docs,
particularly to explain the _username_ concept of the pallet.

---------

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Bastian Köcher <git@kchr.de>

* 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

* fix trigger fingers

* more

* Update frame/example-offchain-worker/README.md

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

* manual rename

* renamse in README.md

* fix template

* Re-generate READMEs to fix doc links; set readme field in package manifests

* Re-generate READMEs to fix doc links; set readme field in package manifests

* Re-generate READMEs to fix doc links; set readme field in package manifests

* Re-generate READMEs to fix doc links; set readme field in package manifests

* Revert stuff that shouldn't have been committed

* Revert stuff that shouldn't have been committed

* Fix parent relative link generation

* Manually remove this incorrect link for now.

* Bump version

* update test-utils crates to be ready for publishing

* adding changelog

* Adding automaticly generated READMEs

* fixing versions

* another version mishap