Take a pass through the multi-builds doc

Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>

modules/rawhide-gating/pages/multibuilds.adoc

@@ -1,10 +1,31 @@
 :experimental:
 = Multibuilds
 
-Some links you might use in the doc. The latter two will appear broken when you build the doc locally because they point to another repo, but will work on the site.
+We are working on this workflow and we will update this page and send
+announcement when it is ready or available for testing.
 
-link:https://docs.pagure.org/greenwave/package-specific-policies.html[package specific policies]
+You can find some hints about the direction we are following in:
 
-xref:ci::quick-start-guide.adoc[CI quick start guide]
+- Our change proposal (the one approved by FESCo):
+  link:https://fedoraproject.org/wiki/Changes/GatingRawhidePackages[]
+- Our project's requirement document
+  link:https://fedoraproject.org/wiki/Infrastructure_2020/Rawhide_Gating[]
 
-xref:ci::index.adoc[CI docs]
+
+== What are multi-builds updates?
+
+Multi-builds updates are builds that are tightly coupled to other build(s).
+
+For compiled package that rely on a certain ABI or soname, it is easy to
+understand how they are tightly coupled. However, non-compiled programs can
+also have this strong dependencies.
+
+For example, the packages link:https://src.fedoraproject.org/rpms/python-urllib3[rpms/python-urllib3]
+and link:https://src.fedoraproject.org/rpms/python-requests/[rpms/python-requests]
+are heavily linked. Updates to python-urllib3 need to take python-requests
+into consideration. Sometime the update is fine, sometime it needs to wait
+for a new version of python-requests, in which case both builds need to be
+tested together as one unit.
+
+These package are candidates for the multi-builds updates workflow. They
+need to be built and tested together.