[CIFS] Add mention of new mount parm (forceuid) to cifs readme

Also update fs/cifs/CHANGES

Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/CHANGES b/fs/cifs/CHANGES
index 227c681..b486898 100644
--- a/fs/cifs/CHANGES
+++ b/fs/cifs/CHANGES
@@ -2,7 +2,10 @@
 ------------
 Client uses server inode numbers (which are persistent) rather than
 client generated ones by default (mount option "serverino" turned
-on by default if server supports it).
+on by default if server supports it).  Add forceuid and forcegid
+mount options (so that when negotiating unix extensions specifying
+which uid mounted does not immediately force the server's reported
+uids to be overridden).
 
 Version 1.58
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