message: improve "Testing the mongocxx driver" docs page
diff: @@ -40,6 +40,41 @@ or, for more detailed output with Catch, run the generated binary:
  ./build/src/mongocxx/test/test_driver
  ```
  +or you can run the ctest command and make use of ctest's various flags.
  +For example:
  +
  +```
  +ctest -V
  +```
  +
  +can be used to run the tests with verbose output, or
  +
  +```
  +ctest -R bson
  +```
  +
  +could be used to run only the bson tests.
  +
  +### Running integration tests
  +
  +Some of the tests require a running mongod instance. For this, first download
  +the [mongodb server](https://www.mongodb.com/download-center).
  +
  +Then deploy a mongod on the default port with the command:
  +
  +```
  +mongod
  +```
  +
  +if it is installed, otherwise navigate to the directory holding the mongod
  +executable, and run:
  +
  +```
  +./mongod
  +```
  +
  +following either command with any flags you wish to use, excluding
  +`--port`. While the mongod is running, run the tests as normal.
  ## Writing new tests
  