Fix some whitespace and quoting

base-notebook/start.sh

@@ -110,13 +110,13 @@ else
                     echo "jovyan:x:$(id -u):" >> /etc/group
                 fi
             else
-                echo 'Container must be run with group root to update passwd file'
+                echo 'Container must be run with group "root" to update passwd file'
             fi
         fi
 
         # Warn if the user isn't going to be able to write files to $HOME.
         if [[ ! -w /home/jovyan ]]; then
-            echo 'Container must be run with group users to update files'
+            echo 'Container must be run with group "users" to update files'
         fi
     else
         # Warn if looks like user want to override uid/gid but hasn't