Apply suggestions from code review

Co-Authored-By: dgw <dgw@technobabbl.es>

sopel/modules/remind.py

@@ -332,7 +332,7 @@ def __eq__(self, other):
     def get_duration(self, today=None):
         """Get the duration between the reminder and ``today``
 
-        :param today: aware datetime to compare to, default to UTC now
+        :param today: aware datetime to compare to; defaults to current time in UTC
         :type today: aware :class:`datetime.datetime`
         :return: The duration, in second, between ``today`` and the reminder.
         :rtype: :class:`int`
@@ -400,7 +400,7 @@ def parse_regex_match(match, default_timezone=None):
                 user_help=True)
 @module.example('.at 00:01 25/12 Open your gift!', user_help=True)
 def remind_at(bot, trigger):
-    """Gives you a reminder at the given times.
+    """Gives you a reminder at the given time.
 
     Takes ``hh:mm:ssTimezone Date message`` where seconds, Timezone, and Date
     are optional.