adds helpful comments to endpoints custom docker file

bshaffer · bshaffer · commit 21844899cfbf · 2016-11-16T14:28:55.000-08:00
diff --git a/endpoints/getting-started/Dockerfile.custom b/endpoints/getting-started/Dockerfile.custom
@@ -1 +1,5 @@
+# The Google App Engine php runtime is Debian Jessie with PHP installed
+# and various os-level packages to allow installation of popular PHP
+# libraries. The source is on github at:
+#   https://github.com/GoogleCloudPlatform/php-docker
 FROM gcr.io/google_appengine/php
