Mod cog: Option to show an extra field with custom content on the ban embed (#6593)

Co-authored-by: Michael Oliveira <34169552+Flame442@users.noreply.github.com>

redbot/cogs/mod/mod.py

@@ -61,6 +61,9 @@ class Mod(
         "default_days": 0,
         "default_tempban_duration": 60 * 60 * 24,
         "track_nicknames": True,
+        "ban_show_extra": False,
+        "ban_extra_embed_title": "Message from staff",
+        "ban_extra_embed_contents": "Please set me",
     }
 
     default_channel_settings = {"ignored": False}