Fix link.

Colin Robertson · web-flow · commit 4e0dd67d1808 · 2019-10-01T17:16:12.000-07:00
diff --git a/docs/cppcx/platform-collections-vector-class.md b/docs/cppcx/platform-collections-vector-class.md
@@ -370,6 +370,6 @@ The last element in a sequence of objects that are used to initialize the curren
 
 ## See also
 
-[Collections (C++/CX)](collections-c-cx)<br/>
+[Collections (C++/CX)](collections-c-cx.md)<br/>
 [Platform Namespace](platform-namespace-c-cx.md)<br/>
 [Creating Windows Runtime Components in C++](/windows/uwp/winrt-components/creating-windows-runtime-components-in-cpp)
