basename: change description and add directory example (#4528)

pages/common/basename.md

@@ -1,11 +1,15 @@
 # basename
 
-> Returns non-directory portion of a pathname.
+> Remove leading directory portions from a path.
 
 - Show only the file name from a path:
 
 `basename {{path/to/file}}`
 
+- Show only the rightmost directory name from a path:
+
+`basename {{path/to/directory/}}`
+
 - Show only the file name from a path, with a suffix removed:
 
 `basename {{path/to/file}} {{suffix}}`