Exclude docs from linting

.flake8

 [flake8]
 max-line-length = 99
 exclude = */migrations, node_modules, stadt/settings/local.py, build,
-  .pybuild, debian/stadtgestalten, debian/tmp, debian/root,
+  .pybuild, debian/stadtgestalten, debian/tmp, debian/root, docs,
   gitlab-ci-build-venv
 ignore = E121,E123,E126,E226,E24,E704,W503,N802

make.d/test.mk

 LINT_PKG_IGNORE_GLOBAL = -path "./debian/*" -o -path "./build/*" -o -path "./.pybuild/*" -o -path "./scripts/*" \
-	-o -path "./.venv/*" -o -path "./gitlab-ci-build-venv/*"
+	-o -path "./.venv/*" -o -path "./gitlab-ci-build-venv/*" -o -path "./docs/*"
 LINT_PKG_PEP420 = $(shell find . -mindepth 2 -type f -name "*.py" -not \( $(LINT_PKG_IGNORE_GLOBAL) \) -print0 | \
 	xargs -0 -n1 dirname | sort | uniq)