[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/VERSION b/VERSION
new file mode 100644
index 0000000..a724a9c
--- /dev/null
+++ b/VERSION
@@ -0,0 +1 @@
+2.4.0-dev