Enable Ruff D (pydocstyle) with pep257 convention (#13326)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

pyproject.toml

@@ -39,6 +39,7 @@ external = ["F821", "NQA", "Y"]
 select = [
     "ARG", # flake8-unused-arguments
     "B", # flake8-bugbear
+    "D", # pydocstyle
     "EXE", # flake8-executable
     "FA", # flake8-future-annotations
     "I", # isort
@@ -108,11 +109,15 @@ ignore = [
     ###
     # Rules we don't want or don't agree with
     ###
-    # Slower and more verbose https://github.com/astral-sh/ruff/issues/7871
-    "UP038", # Use `X | Y` in `isinstance` call instead of `(X, Y)`
+    # We're not a library, no need to document everything
+    "D1", # Missing docstring in ...
+    # Doesn't support split "summary line"
+    "D205", # 1 blank line required between summary line and description
     # Used for direct, non-subclass type comparison, for example: `type(val) is str`
     # see https://github.com/astral-sh/ruff/issues/6465
     "E721", # Do not compare types, use `isinstance()`
+    # Slower and more verbose https://github.com/astral-sh/ruff/issues/7871
+    "UP038", # Use `X | Y` in `isinstance` call instead of `(X, Y)`
     ###
     # False-positives, but already checked by type-checkers
     ###
@@ -139,11 +144,16 @@ ignore = [
     "RUF022",
     "RUF023",
 ]
-# See comment on black's force-exclude config above
 "*_pb2.pyi" = [
+    # Leave the docstrings as-is, matching source
+    "D", # pydocstyle
+    # See comment on black's force-exclude config above
     "E501", # Line too long
 ]
 
+[tool.ruff.lint.pydocstyle]
+convention = "pep257" # https://docs.astral.sh/ruff/settings/#lint_pydocstyle_convention
+
 [tool.ruff.lint.isort]
 split-on-trailing-comma = false
 combine-as-imports = true