Clarify that D417 only checks docstrings with an arguments section (#…

…16494)

## Summary

This came up in #16477

It's not obvious from the D417 rule's documentation that it only checks
docstrings
with an arguments section. Functions without such a section aren't
checked.

This PR tries to make this clearer in the documentation.

crates/ruff_linter/src/rules/pydocstyle/rules/sections.rs

@@ -1167,6 +1167,7 @@ impl AlwaysFixableViolation for MissingSectionNameColon {
 /// a blank line, followed by a series of sections, each with a section header
 /// and a section body. Function docstrings often include a section for
 /// function arguments; this rule is concerned with that section only.
+/// Note that this rule only checks docstrings with an arguments (e.g. `Args`) section.
 ///
 /// This rule is enabled when using the `google` convention, and disabled when
 /// using the `pep257` and `numpy` conventions.