[3.10] bpo-41963: document that ConfigParser strips off comments (GH-26197) (GH-26214)

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Laura Gutierrez Funderburk <58710704+lgfunderburk@users.noreply.github.com>
Co-authored-by: Jürgen Gmach <juergen.gmach@googlemail.com>

(cherry picked from commit 02ee8191263848f8c8999f72286148946b83e5c9)
diff --git a/Lib/configparser.py b/Lib/configparser.py
index 3b4cb5e..2f45e24 100644
--- a/Lib/configparser.py
+++ b/Lib/configparser.py
@@ -908,6 +908,9 @@ def write(self, fp, space_around_delimiters=True):
 
         If `space_around_delimiters' is True (the default), delimiters
         between keys and values are surrounded by spaces.
+
+        Please note that comments in the original configuration file are not
+        preserved when writing the configuration back.
         """
         if space_around_delimiters:
             d = " {} ".format(self._delimiters[0])
@@ -1006,7 +1009,7 @@ def _read(self, fp, fpname):
         Configuration files may include comments, prefixed by specific
         characters (`#' and `;' by default). Comments may appear on their own
         in an otherwise empty line or may be entered in lines holding values or
-        section names.
+        section names. Please note that comments get stripped off when reading configuration files.
         """
         elements_added = set()
         cursect = None                        # None, or a dictionary