[docs] [issue24269] Few improvements to the collections documentation

[Roundup Robot]

Roundup Robot added the comment:

New changeset 4d92ce08de6a by Raymond Hettinger in branch 'default':
Issue #24269: Minor doc fixups.
https://hg.python.org/cpython/rev/4d92ce08de6a

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nosy: +python-dev

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue24269>
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