Add section to Contributing Guide on how to check PEP spelling

Author: CAM-Gerlach

.github/CODEOWNERS

@@ -27,6 +27,8 @@ generate_rss.py         @AA-Turner
 .codespell/             @CAM-Gerlach
 .codespellrc            @CAM-Gerlach
 .pre-commit-config.yaml @CAM-Gerlach
+
+# Git infrastructure
 .gitattributes          @CAM-Gerlach
 .gitignore              @CAM-Gerlach
 

CONTRIBUTING.rst

@@ -56,7 +56,7 @@ position within the project.
 Run pre-commit linting locally
 ------------------------------
 
-If you'd like, you can run the project's basic linting suite locally,
+If you'd like, you can run this repo's basic linting suite locally,
 either on-demand when you choose, or automatically against modified files
 whenever you commit your changes.
 
@@ -84,3 +84,28 @@ every time you commit, install the hooks with ``pre-commit install``.
 Then, whenever you ``git commit``, pre-commit will run and report any issues
 it finds or changes it makes, and abort the commit to allow you to check,
 and if necessary correct them before committing again.
+
+
+Check and fix PEP spelling
+--------------------------
+
+To check for common spelling mistakes in your PEP and automatically suggest
+corrections, you can run the codespell tool through pre-commit as well.
+
+Like the linters, on a system with ``make`` available, it can be installed
+(in the currently-activated environment) and run on all files in the
+repository with a single command, ``make spellcheck``.
+
+For finer control or on other systems, after installing pre-commit as above
+(e.g. ``pip install pre-commit``), you can run it against only the files
+you've modified and not yet committed with
+``pre-commit run --hook-stage manual codespell``, or against all files with
+``pre-commit run --all-files --hook-stage manual codespell``.
+
+**Note**: While fixing spelling mistakes as part of more substantive
+copyediting and proofreading of draft and active PEPs is okay,
+we generally advise against PRs that simply mass-correct minor typos on
+older PEPs that don't significantly impair meaning and understanding,
+as these tend to create a fairly high level of noise and churn for
+PEP readers, authors and editors relative to the amount of practical value
+they provide.

README.rst

@@ -43,12 +43,12 @@ libraries in the ``pep0`` directory.
 Checking PEP formatting and rendering
 =====================================
 
-Avoid committing changes with reStructuredText syntax errors that cause PEP
-generation to fail, or result in major rendering defects relative to what
-you intend. To build the HTML output for your PEP (for example, PEP 12)
+Please don't commit changes with reStructuredText syntax errors that cause PEP
+generation to fail, or result in major rendering defects relative to what you
+intend. To check building the HTML output for your PEP (for example, PEP 12)
 using the current default docutils-based system, run the ``pep2html.py`` script
-with your PEP source file as its argument, e.g. for PEP 12,
-``python -X dev pep2html.py pep-0012.rst``,
+with your PEP source file as its argument (e.g. for PEP 12,
+``python -X dev pep2html.py pep-0012.rst``).
 If you're on a system with ``make``, you can instead simply execute, e.g.,
 ``make pep-0012.rst``.
 To generate HTML for all the PEPs, run the script/``make`` without a PEP