[issue37864] Correct and deduplicate docs on "printable" characters

Change by Greg Price : -- keywords: +patch pull_requests: +15025 stage: -> patch review pull_request: https://github.com/python/cpython/pull/15300 ___ Python tracker ___ _

[issue37864] Correct and deduplicate docs on "printable" characters

New submission from Greg Price : While working on #36502 and then #18236 about the definition and docs of str.isspace(), I looked closely also at its neighbor str.isprintable(). It turned out that we have the definition of what makes a character "printable" documented in three places, giving