Fix link to location.md (#5676)

The `./` there is important to give the correct link when rendered

Author: chtseac

packages/react-router/docs/api/Switch.md

@@ -51,7 +51,7 @@ This is also useful for animated transitions since the matched `<Route>` is rend
 
 ## location: object
 
-A [`location`](location.md) object to be used for matching children elements instead of the current history location (usually the current browser URL).
+A [`location`](./location.md) object to be used for matching children elements instead of the current history location (usually the current browser URL).
 
 ## children: node