Update binlogrouter documentation and release notes

Removed references to removed parameters, and updated release notes.

Documentation/Release-Notes/MaxScale-2.2.1-Release-Notes.md

@@ -9,12 +9,18 @@ For any problems you encounter, please consider submitting a bug
 report at [Jira](https://jira.mariadb.org).
 
 ## Changed Features
+
 ### Binlog server
 
-- MariaDB 10 GTID is always enabled for slave connections.
-- Automatically set binlog storage to 'tree' mode when
-_mariadb10_master_gtid_ option is on.
+* The `mariadb10_slave_gtid` parameter was removed and slave connections can now
+  always register with MariaDB 10 GTID.
 
+* The `binlog_structure` parameter was removed and the binlogs are stored
+  automatically in 'tree' mode when `mariadb10_master_gtid` is enabled.
+
+* If `mariadb10_master_gtid` is enabled, the `transaction_safety` is
+  automatically enabled. In MaxScale 2.2.0, if `transaction_safety` was disabled
+  when `mariadb10_master_gtid` was enabled MaxScale would refuse to start.
 
 ## Dropped Features
 

Documentation/Routers/Binlogrouter.md

@@ -319,10 +319,9 @@ MariaDB> START SLAVE;
 If using GTID request then it's no longer possible to use MASTER_LOG_FILE and
 MASTER_LOG_POS in `CHANGE MASTER TO` command: an error will be reported.
 
-If this feature is enabled, the _mariadb10_slave_gtid_ and
-_transaction_safety_ features will be automatically enabled. The binlog
-files will also be stored in a hierarchical directory tree instead of a
-single directory.
+If this feature is enabled, the _transaction_safety_ option will be
+automatically enabled. The binlog files will also be stored in a
+hierarchical directory tree instead of a single directory.
 
 **Note:**