[VOL-2875] Documentation update

- Updated the main landing page and overview documentation
- Added the lab setup (copied from CORD docs)
- Use forked sphinx-multiversion to publish docs, which allows versions
  to be listed at bottom of sidebar
- Updated logo and favicon, fixed CSS to make logo legible
- Use VERSION file to set the version in the sidebar
- Add more words to dictionary
- removed reload functionality that is nonworking in Sphinx 2.x
- Fixed lint/linkcheck issues

Change-Id: I032e67d76393778fc697944a6d5df9c8cdacbbc4
diff --git a/.gitignore b/.gitignore
index 71e3fcf..27f7af0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,10 +1,12 @@
 # build related
-doc_venv
+venv_docs
 _build
 repos
 
 # subrepos
 bbsim
+ofagent-go
+openolt
 pyvoltha
 voltha-go
 voltha-openolt-adapter
@@ -12,6 +14,7 @@
 voltha-protos
 voltha-system-tests
 voltctl
+cord-tester
 
 # IDEs
 .idea