(#134) Add cake-addin tag to NuGet package

Author: augustoproiete

nuspec/nuget/Cake.Npm.nuspec

@@ -13,7 +13,7 @@
     <icon>icon.png</icon>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <repository type="git" url="https://github.com/cake-contrib/Cake.Npm.git"/>
-    <tags>cake npm cake-build cake-contrib</tags>
+    <tags>cake npm cake-addin cake-build cake-contrib</tags>
     <releaseNotes>https://github.com/cake-contrib/Cake.Npm/releases/tag/1.0.0</releaseNotes>
   </metadata>
   <files>