Fix typo in README

Author: flashcode

README.md

@@ -7,7 +7,7 @@ Postman collections can be imported and used with these Emacs HTTP clients:
 - [verb](https://github.com/federicotdn/verb)
 - [restclient.el](https://github.com/pashky/restclient.el)
 
-You can use your own functions to write other formats (see [Add new output](#add-new-output).
+You can use your own functions to write other formats, see [Add new output](#add-new-output).
 
 ## Installation