docs: try to encourage (netdev?) reviewers

Add a section to netdev maintainer doc encouraging reviewers
to chime in on the mailing list.

The questions about "when is it okay to share feedback"
keep coming up (most recently at netconf) and the answer
is "pretty much always".

Extend the section of 7.AdvancedTopics.rst which deals
with reviews a little bit to add stuff we had been recommending
locally.

Signed-off-by: Jakub Kicinski <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Reviewed-by: Martin Habets <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/process/7.AdvancedTopics.rst

···
 format the request as other developers expect, and will also check to be
 sure that you have remembered to push those changes to the public server.
 
+.. _development_advancedtopics_reviews:
 
 Reviewing patches
 -----------------
···
 get released in this path?" will always work better than stating "the
 locking here is wrong."
 
+Another technique that is useful in case of a disagreement is to ask for others
+to chime in. If a discussion reaches a stalemate after a few exchanges,
+then call for opinions of other reviewers or maintainers. Often those in
+agreement with a reviewer remain silent unless called upon.
+The opinion of multiple people carries exponentially more weight.
+
 Different developers will review code from different points of view.  Some
 are mostly concerned with coding style and whether code lines have trailing
 white space.  Others will focus primarily on whether the change implemented
···
 documentation, adverse effects on performance, user-space ABI changes, etc.
 All types of review, if they lead to better code going into the kernel, are
 welcome and worthwhile.
+
+There is no strict requirement to use specific tags like ``Reviewed-by``.
+In fact reviews in plain English are more informative and encouraged
+even when a tag is provided, e.g. "I looked at aspects A, B and C of this
+submission and it looks good to me."
+Some form of a review message or reply is obviously necessary otherwise
+maintainers will not know that the reviewer has looked at the patch at all!
+
+Last but not least patch review may become a negative process, focused
+on pointing out problems. Please throw in a compliment once in a while,
+particularly for newbies!

Documentation/process/maintainer-netdev.rst

···
 new ``netdevsim`` features must be accompanied by selftests under
 ``tools/testing/selftests/``.
 
+Reviewer guidance
+-----------------
+
+Reviewing other people's patches on the list is highly encouraged,
+regardless of the level of expertise. For general guidance and
+helpful tips please see :ref:`development_advancedtopics_reviews`.
+
+It's safe to assume that netdev maintainers know the community and the level
+of expertise of the reviewers. The reviewers should not be concerned about
+their comments impeding or derailing the patch flow.
+
+Less experienced reviewers are highly encouraged to do more in-depth
+review of submissions and not focus exclusively on trivial or subjective
+matters like code formatting, tags etc.
+
 Testimonials / feedback
 -----------------------