Setup symlink for https://biopython.org/docs/latest/api/

[peterjc]

We will need to update this symlink with each release (or perhaps as part of updating the dev/ documentation via TravisCI?)

Also adds a redirect from https://biopython.org/docs/ (currently page not found error) to the new https://biopython.org/docs/latest/api/ page (had previously considered doing that to the dev docs, this is better in my mind).

Note https://biopython.org/docs/latest/ and https://biopython.org/docs/dev/ etc remain empty (with a page not found error). I hope to have the tutorial built with sphinx there one day, see biopython/biopython#907

[peterjc]

Second commit should have said redirect, not symlink. Maybe just squash-and-merge

[MarkusPiotrowski]

Looks good, still I cannot merge

[peterjc]

Strange - you do seem to be in the Biopython team, and that has write access.

Anyway, merging now, thank you...