Remove master documentation from being indexable by search engines (#58056)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58056
This PR addresses an action item in #3428: disabling search engine
indexing of master documentation. This is desireable because we want to
direct users to our stable documentation (instead of master
documentation) because they are more likely to have a stable version of
PyTorch installed.
Test Plan:
1. run `make html`, check that the noindex tags are there
2. run `make html-stable, check that the noindex tags aren't there
Reviewed By: bdhirsh
Differential Revision: D28490504
Pulled By: zou3519
fbshipit-source-id: 695c944c4962b2bd484dd7a5e298914a37abe787
