Add comments to debug hanging appveyor builds

appveyor.yml

@@ -23,6 +23,14 @@ cache:
   - C:\Ruby%ruby_version%\lib\ruby\gems
   - C:\mingw64
 
+# Uncomment to debug hanging builds via RDP, password can ve found/set under Environment-Variables in appveyor settings!
+#
+# init:
+#   - ps: iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1'))
+#
+# on_finish:
+#   - ps: $blockRdp = $true; iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1'))
+
 install:
   - git clone https://github.com/sass/sassc.git
   - git clone https://github.com/sass/sass-spec.git