docs: add scaffolding for redirects

This allows us to move pages around without breaking links.

Change-Id: Id2be1e6aba9fba376cf217b558ca922d8db1da28

doc/requirements.txt

@@ -9,3 +9,4 @@ openstackdocstheme>=2.2.1 # Apache-2.0
 reno>=3.1.0 # Apache-2.0
 sphinx>=2.0.0,!=2.1.0 # BSD
 sphinxcontrib-svg2pdfconverter>=0.1.0 # BSD
+whereto>=0.3.0 # Apache-2.0

doc/source/_extra/.htaccess

+# No redirects in place yet.

doc/source/conf.py

@@ -58,6 +58,10 @@ pygments_style = 'native'
 html_theme = 'openstackdocs'
 # html_static_path = ['static']
 
+# Add any paths that contain "extra" files, such as .htaccess or
+# robots.txt.
+html_extra_path = ['_extra']
+
 html_theme_options = {
     "show_other_versions": True,
 }

doc/test/redirect-tests.txt

+# No redirects in place yet.

tox.ini

@@ -50,6 +50,7 @@ deps =
 commands =
   rm -rf doc/build
   sphinx-build -W --keep-going -b html doc/source doc/build/html
+  whereto doc/source/_extra/.htaccess doc/test/redirect-tests.txt
 
 [testenv:deploy-guide]
 deps = {[testenv:docs]deps}