added on nodes for rtdb and firestore andmade nodes pass through msg objects with as little changes as possible

rtdb/rtdb-get.html

@@ -52,5 +52,10 @@
 </script>
 
 <script type="text/x-red" data-help-name="rtdb-get">
-    <p>A node that wraps the rtdb-get SDK</p>
+    <p>Get data from a path in the rtdb database </p>
+<p>
+input: {"payload": {"path": "foo/bar"}}
+</p><p>
+output: whatever data was at the path "foo/bar" in the rtdb database</p>
+</p>
 </script>