DOC: Move rebase section to optional. Edit doc contribution section. (pandas-dev#19412)

Author: willingc

doc/source/contributing.rst

@@ -262,8 +262,9 @@ after updating.
 Contributing to the documentation
 =================================
 
-If you're not the developer type, contributing to the documentation is still of
-huge value. You don't even have to be an expert on *pandas* to do so! In fact,
+Contributing to the documentation benefits everyone who uses *pandas*.
+We encourage you to help us improve the documentation, and
+you don't have to be an expert on *pandas* to do so! In fact,
 there are sections of the docs that are worse off after being written by
 experts. If something in the docs doesn't make sense to you, updating the
 relevant section after you figure it out is a great way to ensure it will help
@@ -966,32 +967,6 @@ Now you can commit your changes in your local repository::
 
     git commit -m
 
-Combining commits
------------------
-
-If you have multiple commits, you may want to combine them into one commit, often
-referred to as "squashing" or "rebasing".  This is a common request by package maintainers
-when submitting a pull request as it maintains a more compact commit history.  To rebase
-your commits::
-
-    git rebase -i HEAD~#
-
-Where # is the number of commits you want to combine.  Then you can pick the relevant
-commit message and discard others.
-
-To squash to the master branch do::
-
-    git rebase -i master
-
-Use the ``s`` option on a commit to ``squash``, meaning to keep the commit messages,
-or ``f`` to ``fixup``, meaning to merge the commit messages.
-
-Then you will need to push the branch (see below) forcefully to replace the current
-commits with the new ones::
-
-    git push origin shiny-new-feature -f
-
-
 Pushing your changes
 --------------------
 
@@ -1056,6 +1031,33 @@ updated.  Pushing them to GitHub again is done by::
 This will automatically update your pull request with the latest code and restart the
 :ref:`Continuous Integration <contributing.ci>` tests.
 
+Combining commits (optional)
+----------------------------
+
+*For many contributions, this step will be unneeded. It's included to help
+those who are updating an open pull request.*
+
+If you have multiple commits, you may want to combine them into one commit, often
+referred to as "squashing" or "rebasing".  This is a common request by package maintainers
+when submitting a pull request as it maintains a more compact commit history.  To rebase
+your commits::
+
+    git rebase -i HEAD~#
+
+Where # is the number of commits you want to combine.  Then you can pick the relevant
+commit message and discard others.
+
+To squash to the master branch do::
+
+    git rebase -i master
+
+Use the ``s`` option on a commit to ``squash``, meaning to keep the commit messages,
+or ``f`` to ``fixup``, meaning to merge the commit messages.
+
+Then you will need to push the branch (see below) forcefully to replace the current
+commits with the new ones::
+
+    git push origin shiny-new-feature -f
 
 Delete your merged branch (optional)
 ------------------------------------