Update source/tutorial/install-mongodb-on-windows.txt

Added message to explicitly indicate that mongod.exe started up properly.

Author: sl33nyc

source/tutorial/install-mongodb-on-windows.txt

@@ -135,7 +135,8 @@ To start MongoDB, execute from the :guilabel:`Command Prompt`:
 
    C:\mongodb\bin\mongod.exe
 
-This will start the main MongoDB database process.
+This will start the main MongoDB database process. The ``waiting for connections`` message in the console output
+indicates that the mongod.exe process is running successfully.
 
 .. note::