Merge pull request #869 from Urgau/mcp-update-commands

Update and fix MCPs commands

Author: Kobzol

src/compiler/proposals-and-stabilization.md

@@ -79,21 +79,21 @@ Zulip). See the previous section. To facilitate a machine parsable scanning of t
 please use the following syntax to formally register a concern:
 
 ```
-@rfcbot concern reason-for-concern
+@rustbot concern reason-for-concern
 
 <long description of the concern>
 ```
 
 And the following syntax to lift a concern when resolved:
 
 ```
-@rfcbot resolve reason-for-concern
+@rustbot resolve reason-for-concern
 ```
 
 MCPs can be seconded using:
 
 ```
-@rfcbot second
+@rustbot second
 ```
 
 ##### Who decides whether a concern is unresolved?