Update rc2-to-rtm.rst

install comment and global.json note.

aspnet/migration/rc2-to-rtm.rst

@@ -14,6 +14,16 @@ This migration guide covers migrating an ASP.NET Core RC2 application to ASP.NET
 
 There weren't many significant changes to ASP.NET Core between the RC2 and 1.0 releases. For a complete list of changes, see the `ASP.NET Core 1.0 announcements <https://github.com/aspnet/announcements/issues?q=is%3Aopen+is%3Aissue+milestone%3A1.0.0>`_.
 
+Install the new tools from http://www.dot.net and follow the instructions.
+Update the global.json to 
+.. code-block:: javascript
+{
+  "projects": [ "src", "test" ],
+  "sdk": {
+	"version": "1.0.0-preview2-003121"
+  }
+}
+
 Tools
 -----