[3.7] bpo-30820: Remove incorrect docs for email.contentmanager.raw_data_manager (GH-7631) by miss-islington · Pull Request #7633 · python/cpython

@ZackerySpytz @miss-islington

…nager (pythonGH-7631)

The docs claimed that a list of EmailMessage objects could be
passed to set_content(), but this was never implemented.
(cherry picked from commit 2c071ce)

Co-authored-by: Zackery Spytz <zspytz@gmail.com>