Fixed typo and added/clarified code comment.

Small typo fix (iff -> if). Added code comment, then modified existing code comment to make the intent of the code clearer.

Author: a-vanderbilt

Documentation/Index.md

@@ -288,11 +288,13 @@ On macOS, you can use your app’s **Application Support** directory:
 
 
 ```swift
+
+// set the path corresponding to application support.
 var path = NSSearchPathForDirectoriesInDomains(
     .applicationSupportDirectory, .userDomainMask, true
 ).first! + "/" + Bundle.main.bundleIdentifier!
 
-// create parent directory iff it doesn’t exist
+// create parent directory inside application support if it doesn’t exist
 try FileManager.default.createDirectory(
 atPath: path, withIntermediateDirectories: true, attributes: nil
 )