docs: adding an initial CI documentation

This is actually a first attempt to document our CI, and all this
content was based on the document created by Fabiano Fidencio (kudos to
him). We are just moving the content and discussion from Google Docs to
here.

I used the "poetic license" to add some notes on what I believe our CI
will look like in the future.

Fixes #9006

Co-authored-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>
Signed-off-by: Beraldo Leal <bleal@redhat.com>

tests/cmd/check-spelling/kata-dictionary.dic

@@ -222,6 +222,7 @@ deliverable/AB
 deploy
 dev
 devicemapper/B
+devmapper
 dialer
 dialog/A
 dind/B
@@ -333,6 +334,7 @@ serverless
 signoff/A
 snapcraft/B
 snapd/B
+snapshotters
 stalebot/B
 startup
 stderr/AB