Expand markdown lint rules in omnibus
See the general Documentation guidelines: https://docs.gitlab.com/ee/development/documentation/.
What does this MR do?
Adds more MDL rules to the markdown lint test.
Note: Could not add MD046, MD007, or MD027 due to the failures below.
content/omnibus/development/setup.md:18: MD046 Code block style
content/omnibus/development/setup.md:24: MD046 Code block style
content/omnibus/gitlab-mattermost/README.md:288: MD007 Unordered list indentation
content/omnibus/settings/database.md:206: MD007 Unordered list indentation
content/omnibus/settings/redis.md:47: MD027 Multiple spaces after blockquote symbol
content/omnibus/settings/ssl.md:128: MD027 Multiple spaces after blockquote symbol
Related to #4537 (closed)
Edited by GitLab Release Tools Bot