[docs] Explain how to make the linter know that a file is of INI format

[webknjaz]

I've been staring at the docs that mention that one could lint INI-files here https://nitpick.readthedocs.io/en/latest/plugins.html#ini-files with a few hardcoded examples of such files. I tried applying it to .flake8 and .pylintrc and it worked. But when I did the same for .isort.cfg, nitpick just spit out this:

nitpick-style.toml:1: NIP001  has an incorrect style. Invalid config:
".isort.cfg".settings: Unknown configuration. See https://nitpick.rtfd.io/en/latest/plugins.html#text-files.

I wondered why it'd identify this file as just a text file when it's clearly parseable with cfgparser. Grepping for hardcoded file names recognized as INI didn't help but staring at https://github.com/andreoliwa/nitpick/blob/develop/src/nitpick/plugins/ini.py did. I was lucky to notice identify in the var names even though it wasn't directly imported in that module. This is because I happen to know what that project is.

I quickly confirmed my suspicion with

$ identify-cli .flake8
["file", "flake8", "ini", "non-executable", "text"]
$ identify-cli .isort.cfg 
["file", "non-executable", "text"]

So I've gone ahead and submitted this PR upstream at pre-commit/identify#323.

While that patch will address the immediate problem, I felt like this issue needed to be filed anyway because this situation reveals problems in nitpick itself too.

I think that there are 2 possible action items (non-exclusive):

• mention that identify is used in the docs and suggest the users to submit PRs there to add new file classifications
• implement a config setting in nitpick itself allowing the end-users to specify that some specific file is of a specific (known to them) type and should be linted with a certain plugin

I hope this story provides all the necessary details to be actionable :)

[webknjaz]

• implement a config setting in nitpick itself allowing the end-users to specify that some specific file is of a specific (known to them) type and should be linted with a certain plugin

I've faced a similar issue with another file name — .importlinter (https://import-linter.readthedocs.io/en/stable/usage.html#configuration-file-location). But Anthony doesn't seem keen to make identify aware of it (pre-commit/identify#324 (comment)).

So I'd say that this action item would be important to implement. Plus, since the identify upstream isn't always open to accepting improvements, sending the users there would be rather useless.

I think nitpick could attempt to monkey-patch https://github.com/pre-commit/identify/blob/207d5f7/identify/extensions.py#L260 when adding more files or just let the users specify the file types for things that aren't there or need to be overridden.

[andreoliwa]

I think nitpick could attempt to monkey-patch https://github.com/pre-commit/identify/blob/207d5f7/identify/extensions.py#L260 when adding more files or just let the users specify the file types for things that aren't there or need to be overridden.

Either one of these solutions should work.
Whichever is easier and cleaner to implement.

Duly noted, thanks for yet another bug report. 🙏🏻