weakref documentation does not fully describe proxies

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-12-02.15:18:59.934>
labels = ['3.9', 'docs']
title = 'weakref documentation does not fully describe proxies'
updated_at = <Date 2020-12-02.15:18:59.934>
user = 'https://bugs.python.org/rgov'

bugs.python.org fields:

activity = <Date 2020-12-02.15:18:59.934>
actor = 'rgov'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2020-12-02.15:18:59.934>
creator = 'rgov'
dependencies = []
files = []
hgrepos = []
issue_num = 42542
keywords = []
message_count = 1.0
messages = ['382319']
nosy_count = 2.0
nosy_names = ['docs@python', 'rgov']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue42542'
versions = ['Python 3.9']