manual.texi Clarify meaning of SET TRANSACTION.

Docs/manual.texi:
  Clarify meaning of SET TRANSACTION.

Docs/manual.texi

@@ -36188,16 +36188,15 @@ SET [GLOBAL | SESSION] TRANSACTION ISOLATION LEVEL
 Sets the transaction isolation level for the global, whole session or
 the next transaction.
 
-The default behavior is to set the isolation level for the next (not started)
-transaction.
-
-If you set the @code{GLOBAL} privilege it will affect all new created threads.
-You will need the @strong{process} privilege to do do this.
-
-Setting the @code{SESSION} privilege will affect the following and all
-future transactions.
-
-You can set the default isolation level for @code{mysqld} with
+The default behavior is to set the isolation level for the next (not
+started) transaction.  If you use the @code{GLOBAL} keyword, the statement
+sets the default transaction level globally for all new connections
+created from that point on.  You will need the @strong{process}
+privilege to do do this.  Using the @code{SESSION} keyword sets the
+default transaction level for all future transactions performed on the
+current connection.
+
+You can set the default global isolation level for @code{mysqld} with
 @code{--transaction-isolation=...}. @xref{Command-line options}.
 
 @node Fulltext Search, Query Cache, Transactional Commands, Reference