dev: Some minor renaming to match the strings

add: audit logs for several commands
docs: Updated changelog
fix: xp card user avatar wasn't showing for some users

src/NadekoBot/_common/Attributes/CmdAttribute.cs

@@ -16,6 +16,3 @@ public sealed class CmdAttribute : CommandAttribute
         Summary = memberName.ToLowerInvariant();
     }
 }
-
-[AttributeUsage(AttributeTargets.Method)]
-public sealed class PromptableAttribute: Attribute;