docs

This commit changes the information architecture of event-related
documentation in the Mindshare Committee docs site. Content was changed
minimally; most changes were to mention GitLab instead of Pagure or to
use Discourse/Matrix instead of mailing lists/IRC.

Additionally, the pages in this section now use attributes for several
links. In the event that a link changes in the future, it will be easier
to update URLs from a single place instead of several links becoming
outdated.

I chose to separate the events documentation into a new module because
it provides a greater degree of separation from other content published
in the Mindshare Committee documentation. It can exist as a more
independent part of our docs instead of getting grouped together with
Committee procedures, policies, and onboarding guidance for members.

Signed-off-by: 

Use Camel Case in the navfile

Petr Bokoč