Option to output Markdown warnings as JSON

[robertoaloi]

ex_doc uses the EarMark parser to parse Markdown embedded in Erlang files.

In case of warnings:

-module(test).
-moduledoc """
This file`s Markdown is broken
""".

ex_doc will print them in human-readable format:

mkdir test_ebin
erlc +debug_info -o test_ebin test.erl
ex_doc -f html foobar 1.0.0 test_ebin
    warning: Closing unclosed backquotes ` at end of input
    │
  3 │ This file`s Markdown is broken
    │ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    │
    └─ test.erl:3: (file)

View "html" docs at "doc/index.html"

To use ex_doc programmatically (e.g. in CI), it would be convenient to report warnings in JSON format. For example:

{
  "path": "path/to/test.erl",
  "line": 3,
  "char": 42,
  "severity": "warning",
  "name": "ex_doc",
  "description": "Closing unclosed backquotes ` at end of input",
  "original": "This file`s Markdown is broken",
  "replacement": "This file's Markdown is broken" (maybe one day)
}