[docs] [issue25866] Reference 3. Data Model: miscellaneous minor cleanups on the word "sequence".

Change by Andrei Daraschenka <dorosch.github.io@yandex.ru>: ---------- pull_requests: +16683 stage: needs patch -> patch review pull_request: https://github.com/python/cpython/pull/17175 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25866> _______________________________________