add a new line to config.json

Author: KasimKaizer

exercises/practice/affine-cipher/.meta/config.json

@@ -16,4 +16,5 @@
   "blurb": "Create an implementation of the Affine cipher, an ancient encryption algorithm from the Middle East.",
   "source": "Wikipedia",
   "source_url": "https://en.wikipedia.org/wiki/Affine_cipher"
-}
+}
+