Update nuspec

Author: xabre

.build/Plugin.Badge.nuspec

@@ -14,6 +14,8 @@
     <tags>xamarin xamarin.forms badge tab tabbar monodroid Xamarin.iOS uwp uap android ios windows universal mac macos osx</tags>
     <iconUrl>https://raw.githubusercontent.com/xabre/xamarin-forms-tab-badge/master/icon_small.png</iconUrl>
     <releaseNotes>
+      [2.2.1]
+      - #74: Fix NRE in UpdateBadgeProperties
       [2.2.0]
       - #67: Update to XF 4.0.0.425677
       - #72: Fix Android Warnings