Fix typo

Author: jamhung

README.md

@@ -960,7 +960,7 @@ Guidelines:
 
 * **4.1.4** Use the new `- parameter` syntax as opposed to the old `:param:` syntax (make sure to use lower case `parameter` and not `Parameter`).
 
-* **4.1.5** If you’re doing to be documenting the parameters/returns/throws of a method, document all of them, even if some of the documentation ends up being somewhat repetitive (this is preferable to having the documentation look incomplete). Sometimes, if only a single parameter warrants documentation, it might be better to just mention it in the description instead.
+* **4.1.5** If you’re going to be documenting the parameters/returns/throws of a method, document all of them, even if some of the documentation ends up being somewhat repetitive (this is preferable to having the documentation look incomplete). Sometimes, if only a single parameter warrants documentation, it might be better to just mention it in the description instead.
 
 * **4.1.6** For complicated classes, describe the usage of the class with some potential examples as seems appropriate. Remember that markdown syntax is valid in Swift's comment docs. Newlines, lists, etc. are therefore appropriate.