ci: Add documentation for github actions (#72943)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72943
Adds some documentation about our github actions setup and examples on
how to add workflows / regenerate workflows
Signed-off-by: Eli Uriegas <eliuriegas@fb.com>
Test Plan: Imported from OSS
Reviewed By: kit1980
Differential Revision: D34283475
Pulled By: seemethere
fbshipit-source-id: a4ac9711c19aaf9312361f46db681d4457ab790c
(cherry picked from commit f352bba8e95539d4a49aa207d2816d8bf9a86f50)
