Improve ambiguous docstrings in pkgutil

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-12-05.18:56:47.235>
labels = ['easy', '3.9', '3.10', '3.11', 'type-feature', 'docs']
title = 'Improve ambiguous docstrings in pkgutil'
updated_at = <Date 2022-03-01.01:22:11.805>
user = 'https://bugs.python.org/khock'

bugs.python.org fields:

activity = <Date 2022-03-01.01:22:11.805>
actor = 'slateny'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2021-12-05.18:56:47.235>
creator = 'khock'
dependencies = []
files = []
hgrepos = []
issue_num = 45991
keywords = ['easy']
message_count = 7.0
messages = ['407727', '413883', '413933', '413957', '414076', '414212', '414230']
nosy_count = 4.0
nosy_names = ['docs@python', 'barneygale', 'khock', 'slateny']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45991'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']