Make Feature Liaison optional

As we discussed in the pre-PTG ML thread and on the PTG[2] we don't see too
much value keeping the Feature Liaison mandatory in the spec but we keep
it as an optional way for new contributors to declare that they would like
to be mentored.

[1] http://lists.openstack.org/pipermail/openstack-discuss/2020-May/014917.html
[2] https://etherpad.opendev.org/p/nova-victoria-ptg

Change-Id: I3769eb16fe396404113eba75a64d86e6b3d86f81

README.rst

@@ -229,7 +229,8 @@ Feature Liaison FAQ
 
 In Ussuri, a mandatory "Feature Liaison" section was added to the spec
 template. This section attempts to address some of the questions around this
-concept.
+concept. In Victoria we made filling the section optional but still encourage
+contributors to use it.
 
 What does a Feature Liaison do?
   By signing up to be a feature liaison for a spec, you're agreeing to help

specs/victoria-template.rst

@@ -351,7 +351,7 @@ Other contributors:
 Feature Liaison
 ---------------
 
-Feature work must be sponsored by a member of the `nova core team`_ or
+Ideally feature work is sponsored by a member of the `nova core team`_ or
 other experienced and active nova developer. The purpose of a liaison is
 to:
 
@@ -364,6 +364,10 @@ See the :ref:`feature-liaisons` for more details.
 Feature liaison:
   <name and/or nick>
 
+* Feature liaison is optional. However we suggest to find a liaison for
+  your feature as it will help getting your feature merged. The
+  :ref:`feature-liaisons` has details about how to find a liaison for your
+  work.
 * If you do not already have agreement from a nova developer to act as
   your liaison, you may write "Liaison Needed" here and/or in your
   commit message.