Add missing description about how to specify credentials file

fs/cifs/README

@@ -115,8 +115,11 @@ Once the CIFS VFS support is built into the kernel or installed as a module
 servers: 
 
   mount -t cifs //9.53.216.11/e$ /mnt -o user=myname,pass=mypassword
-  
-after -o the following cifs vfs specific options are supported:
+
+Before -o the option -v may be specified to make the mount.cifs
+mount helper display the mount steps more verbosely.  
+After -o the following commonly used cifs vfs specific options
+are supported:
 
   user=<username>
   pass=<password>
@@ -130,6 +133,18 @@ of the standard mount options "noexec" and "nosuid" to reduce the risk of
 running an altered binary on your local system (downloaded from a hostile server
 or altered by a hostile router).
 
+When using the mount helper mount.cifs, passwords may be specified via alternate
+mechanisms, instead of specifying it after -o using the normal "pass=" syntax
+on the command line:
+1) By including it in a credential file. Specify credentials=filename as one
+of the mount options. Credential files contain two lines
+        username=someuser
+        password=your_password
+2) By specifying the password in the PASSWD environment variable (similarly
+the user name can be taken from the USER environment variable).
+
+If no password is provided, mount.cifs will prompt for password entry
+
 Restrictions
 ============
 Servers must support the NTLM SMB dialect (which is the most recent, supported 
@@ -194,6 +209,9 @@ A partial list of the supported mount options follows:
   suid          Allow remote files on this mountpoint with suid enabled to 
 		be executed (default for mounts when executed as root,
 		nosuid is default for user mounts).
+  credentials   (allow valid when the cifs mount helper, mount.cifs, is
+		installed. Specifies the name of the credential file which 
+		will be read to obtain the userid and password.
 
 Misc /proc/fs/cifs Flags and Debug Info
 =======================================