Add 0.16 docs

[NicolasHug]

These are the docs taken from the currently-last commit of the release branch: https://github.com/pytorch/text/actions/runs/6319000250

I downloaded the generated docs and manually copy/pasted them in a new 0.16 folder in the gh-pages branch.

Also edited the symlink and versions page, + a bunch of automatic version hash renaming.

CC @svekars

[pytorch-bot[bot]]

:link: Helpful Links

:test_tube: See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/text/2207

• :page_facing_up: Preview Python docs built from this PR

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