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

Change by Alex <alexpclarkson@gmail.com>: ---------- pull_requests: +16685 pull_request: https://github.com/python/cpython/pull/17177 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25866> _______________________________________