Update php.md - /.dockerinit was removed in v1.11 so the test always results...

Update php.md - /.dockerinit was removed in v1.11 so the test always results in an early exit https://github.com/docker/docker/pull/19490

doc/ci/examples/php.md

@@ -40,7 +40,7 @@ repository with the following content:
 #!/bin/bash
 
 # We need to install dependencies only for Docker
-[[ ! -e /.dockerenv ]] && [[ ! -e /.dockerinit ]] && exit 0
+[[ ! -e /.dockerenv ]] && exit 0
 
 set -xe