Update release notes and limitations regarding the KILL-command support

Documentation/About/Limitations.md

@@ -47,7 +47,18 @@ transaction or change the autocommit mode using a prepared statement.
 
 ### Limitations with MySQL Protocol support (MySQLClient)
 
-Compression is not included in the MySQL server handshake.
+* Compression is not included in the MySQL server handshake.
+
+* MariaDB MaxScale will intercept `KILL <thread_id>` statements which are of the
+form `KILL 3`, `KILL CONNECTION 321` and `KILL QUERY 8`. These queries are not
+routed to backends because the `<thread_id>` sent by the client does not equal a
+backend id. MaxScale reacts to a thread kill command by killing the session with
+the given id if the user and host of the issuing session and the target session
+match. Query kill command is not supported and results in an error message. For
+MaxScale to recognize the *KILL* statement, the statement must start right after
+the command byte, have no comments and have minimal whitespace. These
+limitations are in place to limit the parsing MaxScale needs to do to every
+query.
 
 ## Authenticator limitations
 

Documentation/Release-Notes/MaxScale-2.2.0-Release-Notes.md

@@ -68,6 +68,13 @@ The MySQL backend protocol module now supports sending a proxy protocol header
 to the server. For more information, see the server section in the
 [Configuration guide](../Getting-Started/Configuration-Guide.md).
 
+### KILL command support
+
+The MySQL client protocol now detects `KILL <thread_id>` statements (binary and
+query forms) and kills the MaxScale session with the given id. This feature has
+some limitations, see [Limitations](../About/Limitations.md) for more
+information.
+
 ## Bug fixes
 
 [Here is a list of bugs fixed since the release of MaxScale 2.1.X.]()