fix UID mapping for mount.cifs command

storage/access.markdown

@@ -137,10 +137,10 @@ sudo mount -t cifs -o domain=AD,username=USERNAME,vers=3.0 //SERVERNAME/SHARENAM
 ```
 
 
-To map the `uid` to your local User:
+To map `uid` and `gid` to your local user:
 
 ```
-sudo mount -t cifs -o domain=AD,username=USERNAME,vers=3.0,uid=$(id -u),gid=$(id -g) //home.phys.ethz.ch/homes /media/dphys
+sudo mount -t cifs -o domain=AD,username=USERNAME,vers=3.0,uid=$(id -u $UID),gid=$(id -g $UID) //home.phys.ethz.ch/homes /media/dphys
 ```
 
 ## smbclient