Upload docusaurus [wip]

[cmdcolin]

This is a big overhaul of the documentation that transports gmod wiki to use docusaurus. Aided by @scottcain initial markdown translation

This PR

• Reimplements homepage staying fairly faitthful to the original site design
• Imports wordpress blogposts to markdown. Note that the links to old releases do not work currently but also they do not work on the main site anyways (links to older releases such as 1.11 branch and earlier do not work)
• Allows updating documentation by putting [update docs] in commit message
• Migrate existing quick start guide into docs (e.g. this one does not get deleted) adds a new quick-start guide based only on indexed file formats
• Break the large configuration guide into pages. This is maybe debatable decision for the docs but it seems pretty manageable and organized in some sense, but at perhaps the expense of "ctrl+f" the entire doc
• Break the large faq into pages, same thing
• Move some more uncommon stuff from the "config guide" guise into a different "Other topics" section
• Import the featureglyphs.htm into the htmlfeatures doc :)

View https://jbrowse.org/documentation/

Feedback welcome

[rbuels]

Don't forget to make a limited user on jbrowse.org for travis to use for deploys

[cmdcolin]

I think starting tomorrow I'll be updating website in prep for release