Add simple usage to email module

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-12-06.10:44:20.384>
labels = ['type-feature', '3.10', 'docs']
title = 'Add simple usage to email module'
updated_at = <Date 2021-12-06.16:51:58.791>
user = 'https://github.com/tarao1006'

bugs.python.org fields:

activity = <Date 2021-12-06.16:51:58.791>
actor = 'tarao1006'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2021-12-06.10:44:20.384>
creator = 'tarao1006'
dependencies = []
files = []
hgrepos = []
issue_num = 45994
keywords = []
message_count = 2.0
messages = ['407803', '407839']
nosy_count = 3.0
nosy_names = ['eric.smith', 'docs@python', 'tarao1006']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45994'
versions = ['Python 3.10']