Lint docs with doc8

.circleci/config.yml

@@ -23,6 +23,7 @@ jobs:
       - run:
           shell: /bin/bash -e
           command: pipenv run jinjalint --parse-only wagtail | grep -v 'welcome_page.html:6:70' | tee /dev/tty | wc -l | grep -q '0'
+      - run: pipenv run doc8 --ignore D001 docs
       - run: DATABASE_NAME=wagtail.db pipenv run python -u runtests.py
 
   frontend:

docs/Makefile

@@ -59,6 +59,9 @@ spelling:
 	@echo
 	@echo "Spellcheck complete."
 
+lint:
+	doc8 --ignore D001 --ignore-path _build
+
 dirhtml:
 	$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
 	@echo

docs/releases/0.8.rst

@@ -92,7 +92,7 @@ and the ``validators`` attribute of the 'file' field - that is, the line:
 
 should become:
 
-    .. code-block:: python
+.. code-block:: python
 
     ('file', models.ImageField(upload_to=wagtail.wagtailimages.models.get_upload_to,
         width_field='width', height_field='height', verbose_name='File')),

setup.py

@@ -60,6 +60,7 @@ testing_extras = [
     'isort==4.2.5',
     'flake8-blind-except==0.1.1',
     'flake8-print==2.0.2',
+    'doc8==0.8.1',
 
     # For templates linting
     'jinjalint>=0.5',