Tweaked version of CONTRIBUTING.md from preservim/vim-markdown#60

CONTRIBUTING.md

These contributing guidelines were accepted rather late in the history of this plugin, after much code had already been written.

If you find any existing behavior which does not conform to these guidelines, please correct it and send a pull request.

General Rules

Every non local identifier must start with g:vim_markdown_.

Documentation

Every new feature must be documented under in the README.md. Documentation must be written in GFM since Github itself is the primary to HTML converter used. In particular, remember that GFM adds line breaks at single newlines, so just forget about the 70 characters wide rule.

Markdown Flavors

There are many flavors of markdown, each one with an unique feature set. This plugin uses the following strategy to deal with all those flavors:

• Features from the original markdown are turned on by default. They may not even have an option that turns them off.

• Features from other markdown flavors must have an option that turns them on or off. If the feature is common enough across multiple versions of markdown, it may be turned on by default. This shall be decided by the community when the merge request is done.

• If possible, cite the exact point in the documentation of the flavor where a feature is specified. If the feature is not documented, you may also reference the source code itself of the implementation. This way, people who do not know that flavor can check if your implementation is correct.

• Do not use the name of a flavor for a feature that is used across multiple flavors. Instead, create a separate flavor option, that automatically sets each feature.

  For example, fenced code blocks (putting code between pairs of three backticks) is not part of the original markdown, but is supported by GFM and Jekyll.

  Therefore, instead of creating an option g:vim_markdown_gfm_fenced_code_block, and an option g:vim_markdown_jekyll_fenced_code_block, create a single option g:vim_markdown_fenced_code_block.

  Next, if there are many more than one Jekyll feature options, create a g:vim_markdown_jekyll option that turns them all on at once.

Tests

All new features must have tests. While we don't require unit tests, which are too hard to do in certain cases, you should create a test under the test/ directory with a predictable name which allows other users to quickly test your feature. Good tests should explain their expected input / output behavior. Failing test should be marked with FAIL somewhere near the test, possibly explaining why it fails. For example:

## Links

[Link text](link URL)

... more correct link tests ...

###### FAIL: should not be highlighted as a link

Text (with parenthesis) alone should not be highlighted as a link. (Issue #57)

... more failed link tests ...

## Code Blocks