[docs] added tox testing text to maintainer notes
was previously in a separate file
## Code Testing
-See [docs/code-testing.md](https://github.com/googlefonts/fontbakery/blob/master/docs/code-testing.md)
+`tox` and `coverage` are used to execute the Font Bakery test suite and line coverage assessment, respectively.
+
+Use the following command to run all tests:
+
+```
+$ tox
+```
+
+The coverage report can be found at the end of the test results that are printed to the standard output/error stream.
+
+Continuous integration testing is performed on Travis CI. Test jobs can be found at [https://travis-ci.org/googlefonts/fontbakery](https://travis-ci.org/googlefonts/fontbakery).
## Updating the distribution package
