[doc] Fix missing commas in signatures (#23693)

* Fix star in signatures

* Fix comma in signatures

Author: andresdelfino

Doc/library/datetime.rst

@@ -1219,7 +1219,7 @@ Instance methods:
 
 .. method:: datetime.replace(year=self.year, month=self.month, day=self.day, \
    hour=self.hour, minute=self.minute, second=self.second, microsecond=self.microsecond, \
-   tzinfo=self.tzinfo, * fold=0)
+   tzinfo=self.tzinfo, *, fold=0)
 
    Return a datetime with the same attributes, except for those attributes given
    new values by whichever keyword arguments are specified. Note that
@@ -1783,7 +1783,7 @@ Other constructor:
 Instance methods:
 
 .. method:: time.replace(hour=self.hour, minute=self.minute, second=self.second, \
-   microsecond=self.microsecond, tzinfo=self.tzinfo, * fold=0)
+   microsecond=self.microsecond, tzinfo=self.tzinfo, *, fold=0)
 
    Return a :class:`.time` with the same value, except for those attributes given
    new values by whichever keyword arguments are specified. Note that

Doc/library/email.contentmanager.rst

@@ -116,7 +116,7 @@ Currently the email package provides only one concrete content manager,
       decoding the payload to unicode.  The default error handler is
       ``replace``.
 
-   .. method:: set_content(msg, <'str'>, subtype="plain", charset='utf-8' \
+   .. method:: set_content(msg, <'str'>, subtype="plain", charset='utf-8', \
                            cte=None, \
                            disposition=None, filename=None, cid=None, \
                            params=None, headers=None)