Docs (linter.md): clarify that Python files are always searched for in subdirectories

[anordin95]

Nits related to clarity of which files are linted

Hi!

I noticed no mention of recursing through sub-dirs and only the fourth example: ruff check path/to/code/ included the phrase: "and any subdirectories" leading me to believe only providing a path would recurse and the others would not. I don't think that's the actual behavior. It does feel a bit repetitive to say so in each example and in the intro paragraph, but I do somewhat like the clarity.

Also, I opted to remove the "all" from "Lint all files in the current directory." (and others) since I presume it doesn't lint all files, only "all discovered Python files". Without the "all", I think it's clear many files will be linted, and it gives
a hint that further logic exists for filtering.

[AlexWaygood]

I can see how this is unclear on main, but the suggested rewording here does feel a little repetitive now. What about something like this?

`ruff check` is the primary entrypoint to the Ruff linter. It accepts a list of files or
directories, and lints all discovered Python files, optionally fixing any fixable errors.
When linting a directory, Ruff searches for Python files recursively in that directory
and all its subdirectories:

```console
$ ruff check                  # Lint all files in the current directory.
$ ruff check --fix            # Lint all files in the current directory, and fix any fixable errors.
$ ruff check --watch          # Lint all files in the current directory, and re-lint on change.
$ ruff check path/to/code/    # Lint all files in `path/to/code`
```

[anordin95]

Mmm, yes that's better! Well done :)

[anordin95]

PS do you have opinions on:
Lint all files in the current directory.
vs.
Lint files starting from the current directory.

I prefer the latter since it hints there is some filtering and recursion without losing clarity, e.g. only Python files, respect .gitignore, etc.

[AlexWaygood]

Thanks!