bot: eliminate problematic xrefs from SopelWrapper docs

The formatting, in particular, is what was problematic here. Sphinx
doesn't provide a way to negate the monospace formatting of a :meth:
reference when using a custom title, so the only way to avoid having
random monospace words in the middle of this paragraph is... rewriting
to eliminate the xrefs.

Which is to say, if there's a better answer to this question
(https://stackoverflow.com/q/45741326/5991) in the future, we can put
this back the way it was.

sopel/bot.py

@@ -1230,9 +1230,9 @@ class SopelWrapper:
                               (e.g. plugin tag)
 
     This wrapper will be used to call Sopel's triggered commands and rules as
-    their ``bot`` argument. It acts as a proxy to :meth:`send messages<say>`
-    to the sender (either a channel or in a private message) and even to
-    :meth:`reply to someone<reply>` in a channel.
+    their ``bot`` argument. It acts as a proxy, providing the ``trigger``'s
+    ``sender`` (source channel or private message) as the default
+    ``destination`` argument for overridden methods.
     """
     def __init__(self, sopel, trigger, output_prefix=''):
         if not output_prefix: