Improve multi-line suggestion docs

See merge request gitlab-org/gitlab-ce!27465

(cherry picked from commit 28e42f1c)

6ad6cc40 Improve multi-line suggestion docs

Oswaldo Ferreir authored 5 years ago and Douwe Maan committed 5 years ago

- added suggestions to mock data
- fixed props to be not required

Fixes #56864

copied from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/25633

Added documentation for starting a discussion from a
non-discussion comment feature.

Evan Read authored 6 years ago and Achilleas Pipinellis committed 6 years ago

Markdown renderers find it easier to determine
where lists start and end when lists are surrounded
by new lines.

For consistency, also ensure entries in the list
are aligned when they span multipls lines.

Notes/Discussions filters documentation was missingg.

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/27070

Deprecate "chat commands" in favor of "slash commands"

We looked for things like:

 - `slash commmand`
 - `slash_command`
 - `slash-command`
 - `SlashCommand`

- Move to dicsussions/index.md
- Bring back previous path with a link to new location
- Reorder sections