Blocking tasks are now capital TODO (compared to non-blocking todo).
Updated some of the todos.
Added note about which intel synth does which families.
Rename extended Yosys universe to Yosys family.
Added brief text to landing page, and also a note about the restructure and where to find old docs.
Moved todolist above ToC in preparation for disabling it in the config (so that it doesn't need it's own header).
Fixed pdf build, was previously breaking on trying to include the svg badges.
Now includes usage output, (hopefully) generated by the tool during the docs build process so it will always be up to date.
Included in makefile as `docs/usage` target.
Also some updates/additions to the description text, esp `yosys-filterlib` and `yosys-smtbmc`.
Krystine Sherwin