[Docs] Add instructions to create keymap before proceeding (qmk#14945)

Co-authored-by: filterpaper <filterpaper@localhost>

docs/newbs_getting_started.md

@@ -194,7 +194,7 @@ You can also set your default keymap name. Most people use their GitHub username
 
     qmk config user.keymap=<github_username>
 
-After this you can leave those arguments off and compile your keyboard like this:
+The keyboard can now be compiled without arguments using the following command after creating your keymap in the next section:
 
     qmk compile