Document the pypi user and how to manage it. (#1049)

* Document the pypi user and how to manage it.

The mention in the release config isn't easily found and I want to make
sure there is some reference for how to manage the account.

* Revert "Document the pypi user and how to manage it."

This reverts commit bfcb3ac.

* Document the pypi user and how to manage it.

This time without reformating everything.

Author: rickeylev

DEVELOPING.md

@@ -21,4 +21,12 @@ those with only bug fixes and other minor changes bump the patch digit.
 #### After release creation in Github
 
 1. Ping @philwo to get the new release added to mirror.bazel.build. See [this comment on issue #400](https://github.com/bazelbuild/rules_python/issues/400#issuecomment-779159530) for more context.
-1. Announce the release in the #python channel in the Bazel slack (bazelbuild.slack.com). 
+1. Announce the release in the #python channel in the Bazel slack (bazelbuild.slack.com).
+
+## Secrets
+
+### PyPI user rules-python
+
+Part of the release process uploads packages to PyPI as the user `rules-python`.
+This account is managed by Google; contact [email protected] if
+something needs to be done with the PyPI account.