Get a slot on wikimo front page

[pascalchevrel]

We should have a slot on the wiki front page for discoverability of the pages that our devs and contributors are always looking for, namely:

• Release owners
• Release Calendar
• Release Notes
• Release process

The front page is not editable and clearly unmaintained so we need to check who can update it or if we can get editing rights on it.

[pascalchevrel]

https://bugzilla.mozilla.org/show_bug.cgi?id=1452918

[pascalchevrel]

done