Update 02-navigating-the-filesystem.md

Change to 'ls' command prompt - expand and explain abbreviation

Author: AdrienneCanino

_episodes/02-navigating-the-filesystem.md

@@ -39,7 +39,7 @@ $ pwd
 {: .output}
 
 The output will be a path to your home directory. Let's check if we recognise it
-by listing the contents of the directory. To do that, we use the `ls` command:
+by looking at the contents of the directory. To do that, we use the `ls` command. This stands for "list" and the result is a print out of all the contents in the directory:
 
 ~~~
 $ ls