Also fix parameter name in parameter docs.

Follow-on to commit 36832a8.

(cherry picked from commit 4c82b77)

Author: amartini51

stdlib/public/core/Collection.swift

@@ -1479,7 +1479,7 @@ extension Collection {
   ///     // Prints "[10, 20, 30, 40]"
   ///
   /// - Parameter position: The index of the last element to include in the
-  ///   resulting subsequence. `end` must be a valid index of the collection
+  ///   resulting subsequence. `position` must be a valid index of the collection
   ///   that is not equal to the `endIndex` property.
   /// - Returns: A subsequence up to, and including, the `end` position.
   ///