Complete a grammatical sentence in Collections.md

Guides/Collections.md

@@ -22,7 +22,7 @@ This type of functionality can be useful for examples and testing, and also for
 
 Three categories of initializers will be added to provide initializers for those three primary types: `Array`, `Dictionary` and `Set`. However these initializers can be written in a generic fashion such that they can apply to all similar collections.
 
-`RangeReplaceableCollection` will gain a new that constructs a collection given an `AsyncSequence`. This will allow for creating arrays from asynchronous sequences but also allow for creating types like `Data` or `ContiguousArray`. Because of the nature of asynchronous sequences, this initializer must be asynchronous and declare that it rethrows errors from the base asynchronous sequence.
+`RangeReplaceableCollection` will gain a new initializer that constructs a collection given an `AsyncSequence`. This will allow for creating arrays from asynchronous sequences but also allow for creating types like `Data` or `ContiguousArray`. Because of the nature of asynchronous sequences, this initializer must be asynchronous and declare that it rethrows errors from the base asynchronous sequence.
 
 ```swift
 extension RangeReplaceableCollection {