Fix links that assumed branch "dev" exists (which doesn't) (#1725)

* Fix links that assumed branch "dev" exists (which doesn't)

* Adressed comments [skip ci]

src/Microsoft.AspNetCore.SpaServices/README.md

@@ -9,7 +9,7 @@ This package enables:
  * [**Hot module replacement**](#webpack-hot-module-replacement) so that, during development, your code and markup changes will be pushed to your browser and updated in the running application automatically, without even needing to reload the page
  * [**Routing helpers**](#routing-helper-mapspafallbackroute) for integrating server-side routing with client-side routing
 
-Behind the scenes, it uses the [`Microsoft.AspNetCore.NodeServices`](https://github.com/aspnet/JavaScriptServices/tree/dev/src/Microsoft.AspNetCore.NodeServices) package as a fast and robust way to invoke Node.js-hosted code from ASP.NET Core at runtime.
+Behind the scenes, it uses the [`Microsoft.AspNetCore.NodeServices`](https://github.com/aspnet/JavaScriptServices/tree/master/src/Microsoft.AspNetCore.NodeServices) package as a fast and robust way to invoke Node.js-hosted code from ASP.NET Core at runtime.
 
 ### Requirements
 

src/Microsoft.AspNetCore.SpaServices/Webpack/ConditionalProxyMiddleware.cs

@@ -9,7 +9,7 @@ using Microsoft.AspNetCore.Http;
 namespace Microsoft.AspNetCore.SpaServices.Webpack
 {
     /// <summary>
-    /// Based on https://github.com/aspnet/Proxy/blob/dev/src/Microsoft.AspNetCore.Proxy/ProxyMiddleware.cs
+    /// Based on ProxyMiddleware from https://github.com/aspnet/Proxy/.
     /// Differs in that, if the proxied request returns a 404, we pass through to the next middleware in the chain
     /// This is useful for Webpack middleware, because it lets you fall back on prebuilt files on disk for
     /// chunks not exposed by the current Webpack config (e.g., DLL/vendor chunks).