chore: put check-remote script back to fix docs build (mongodb#3739)

Author: dariakp

etc/check-remote.sh

@@ -0,0 +1,6 @@
+#! /bin/bash
+
+if git remote get-url --push origin | grep -qv "github.com:mongodb\|github.com/mongodb"; then
+    echo "git remote does not match node-mongodb-native.  are you working off of a fork?"
+    exit 1
+fi