fish_greeting: highlight "help" in in green, like it used to be

This was changed in b9d2e4d with no obvious motivation, and the
translation strings still have the old version.

share/functions/__fish_config_interactive.fish

@@ -21,7 +21,7 @@ function __fish_config_interactive -d "Initializations that should be performed
 
     if not set -q fish_greeting
         set -l line1 (_ 'Welcome to fish, the friendly interactive shell')
-        set -l line2 \n(_ 'Type `help` for instructions on how to use fish')
+        set -l line2 \n(printf (_ 'Type %shelp%s for instructions on how to use fish') (set_color green) (set_color normal))
         set -U fish_greeting "$line1$line2"
     end