refactor(docker): use arg to set rulebook name

ref: #3 #1

includes/entrypoint.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+set -e
+
+if [ $# -eq 0 ]; then
+
+    cd ${HOME};
+
+    ansible-rulebook \
+        -r nofusscomputing.git_events.${GIT_EVENT_RULEBOOK_NAME} \
+        --env-vars PROBLEM_MATCHER_PORT,PROBLEM_MATCHER_TOKEN \
+        -v;
+
+else
+
+  exec "$@"
+
+fi