Add docs link for BaseInstallers

Author: aaaaalbert

Operating/BaseInstallers.md

@@ -1,4 +1,5 @@
 # Building Base Installers
 
 The base installer building and packaging information for RepyV2 is available
-from the [`installer-packaging` repo's README](https://github.com/SeattleTestbed/installer-packaging/blob/master/README.md).
+from the [`installer-packaging` repo's README](https://github.com/SeattleTestbed/installer-packaging/blob/master/README.md)
+and the [`custominstallerbuilder` setup docs](CustomInstallerBuilder/Installation.md#building-base-installers).