Add track Contributing Guide and Generator documentation

[cmccandless]

No description provided.

[kytrinyx]

This looks great. I can't speak to the python-specifics, but it is lovely to see thorough documentation.

[yawpitch]

Excellent work ... only thing I'd think about changing is maybe replacing "fake_exercise" with something like "[EXERCISE]", and slightly re-arranging the order of the extra files to keep them related to the order of the files they modify.

exercises/[EXERCISE]/
├── [EXERCISE].py
├── [EXERCISE]_test.py
├── example.py
├── .meta
│   ├── template.j2
│   ├── additional_tests.json
│   └── hints.md
└── README.md

Plus updating the table to reflect and be a little bit more explicit:

• fake_exercise.py Solution stub manually created by the implementer. (See exercises/hello-world/hello_world.py)
• fake_exercise_test.py Exercise test suite; automatically generated if .meta/template.j2 is present, otherwise manually created by the implementer. (See exercises/hello-world/hello_world_test.py)
• example.py Example solution manually created by the implementer and used to automatically verify the [EXERCISE]_test.py suite. (See exercises/hello-world/example.py)
• .meta/template.j2 Test generation template; if present used to automatically generate [EXERCISE]_test.py. (See exercises/hello-world/.meta/template.j2)
• .meta/additional_tests.json Defines additional track-specific test cases; if .meta/template.j2 is also present these tests will be incorporated into the automatically generated [EXERCISE]_test.py. (See exercises/word-count/.meta/additional_tests.json)
• .meta/hints.md Contains track-specific hints that are automatically included in the generated README.md file. (See exercises/high-scores/.meta/hints.md)
• README.md Exercise README automatically generated by the configlet tool. (See exercises/hello-world/hello_world.py)

I'd think grouping them together buy functionality makes the whole easier to understand than lexical ordering as they'd get from tree.

That said I'd still merge it as is if you don't agree.

[cmccandless]

maybe replacing "fake_exercise" with something like "[EXERCISE]", and slightly re-arranging the order of the extra files to keep them related to the order of the files they modify.

Initially I had example_exercise, but that looked confusing with example_exercise.py and example.py. I like your idea better.

[yawpitch]

Changes look great!