Enforce some pydocstyle lints with flake8-docstrings

There are some ones we *would* like to enforce, like
    D401 First line should be in imperative mood
but have too many false positives, so I left them out.

.pre-commit-config.yaml

@@ -25,7 +25,9 @@ repos:
     hooks:
     -   id: flake8
         language_version: python3
-        additional_dependencies: [flake8-typing-imports==1.9.0]
+        additional_dependencies:
+          - flake8-typing-imports==1.9.0
+          - flake8-docstrings==1.5.0
 -   repo: https://github.com/asottile/reorder_python_imports
     rev: v2.3.0
     hooks:

tox.ini

@@ -154,7 +154,17 @@ commands = python scripts/publish-gh-release-notes.py {posargs}
 
 [flake8]
 max-line-length = 120
-extend-ignore = E203
+extend-ignore =
+    ; whitespace before ':'
+    E203
+    ; Missing Docstrings
+    D100,D101,D102,D103,D104,D105,D106,D107
+    ; Whitespace Issues
+    D202,D203,D204,D205,D209,D213
+    ; Quotes Issues
+    D302
+    ; Docstring Content Issues
+    D400,D401,D401,D402,D405,D406,D407,D408,D409,D410,D411,D412,D413,D414,D415,D416,D417
 
 [isort]
 ; This config mimics what reorder-python-imports does.