Update .nuspec file to include dist/powebi.d.ts file in the scripts/typings folder.

Author: mattmazzola

PowerBI.JavaScript.nuspec

@@ -17,5 +17,6 @@
   <files>
     <file src="dist\powerbi.js" target="content\scripts" />
     <file src="dist\powerbi.min.js" target="content\scripts" />
+    <file src="dist\powerbi.d.ts" target="content\scripts\typings" />
   </files>
 </package>