remove reference to VSIX Gallery

docs/installation.md

@@ -1,18 +1,16 @@
 # Installation
 
-There are two versions of the extension. We recommend using the release version unless you want to test something that is only in the beta version. While it is possible to have both versions installed at once, some functionality may not work correctly if both are enabled (Extensions > Manage Extensions) at the same time.
+Get the official release from the VS Marketplace.
 
 ## Official Release
 
-Get the toolkit from the [Visual Studio Marketplace](https://marketplace.visualstudio.com/items?itemName=MattLaceyLtd.RapidXamlToolkit) or by searching inside Visual Studio.
+Get the toolkit from the [Visual Studio Marketplace](https://marketplace.visualstudio.com/items?itemName=MattLaceyLtd.RapidXamlToolkit) or by searching inside Visual Studio (Extensions > Manage Extensions).
 
 _If you had it, the preview version should be uninstalled first._
 
 ## Beta builds
 
-Automated builds with the [latest development version](http://vsixgallery.com/extension/RapidXamlToolkit.0dc8e86a-836b-47e5-aa3f-f5e71c15e37a/) of all functionality are available from the [VSIX Gallery](https://www.vsixgallery.com/feedguide). These are produced every time PRs are merged that contain code changes.
-
-_A version distributed via MyGet is no longer available._
+No longer available. - sorry.
 
 ***