Update README and homepage for v0.5

[sotte]

[sotte]

I'm updating the documentation and I'm constantly thinking that it would be much nicer to write the documentation in orgmode format instead of vim-help format. Then the REAME.org (and maybe the homepage) would be the first part of the documentation.

We'd lose the "jump to tag" function. However, once we have the internal links working they could replace this functionality.

Dunno...