Fix more places where server is used instead of guild in docstrings.

discord/guild.py

@@ -301,7 +301,7 @@ class Guild(Hashable):
 
     @property
     def splash_url(self):
-        """Returns the URL version of the server's invite splash. Returns an empty string if it has no splash."""
+        """Returns the URL version of the guild's invite splash. Returns an empty string if it has no splash."""
         if self.splash is None:
             return ''
         return 'https://cdn.discordapp.com/splashes/{0.id}/{0.splash}.jpg?size=2048'.format(self)

discord/message.py

@@ -486,7 +486,7 @@ class Message:
 
         Add a reaction to the message.
 
-        The emoji may be a unicode emoji or a custom server :class:`Emoji`.
+        The emoji may be a unicode emoji or a custom guild :class:`Emoji`.
 
         You must have the :attr:`Permissions.add_reactions` permission to
         add new reactions to a message.
@@ -523,7 +523,7 @@ class Message:
 
         Remove a reaction by the member from the message.
 
-        The emoji may be a unicode emoji or a custom server :class:`Emoji`.
+        The emoji may be a unicode emoji or a custom guild :class:`Emoji`.
 
         If the reaction is not your own (i.e. ``member`` parameter is not you) then
         the :attr:`Permissions.manage_messages` permission is needed.