Clarified the role of .gitkeep files and their naming

episodes/04-changes.md

@@ -577,8 +577,7 @@ Two important facts you should know about directories in Git.
 
   Note, our newly created empty directory `cakes` does not appear in
   the list of untracked files even if we explicitly add it (*via* `git add`) to our
-  repository. This is the reason why you will sometimes see `.gitkeep` files
-  in otherwise empty directories.
+  repository. This is the reason why you will sometimes see `.gitkeep` files in otherwise empty directories. The sole purpose of `.gitkeep` files is to populate a directory so that Git adds it to the repository. The name `.gitkeep` is just a convention, and in fact, you can name these files anything you like.
 
 2. If you create a directory in your Git repository and populate it with files,
   you can add all files in the directory at once by: