Fix docstring in ruff_annotate_snippets (#15748)

## Summary

Found a comment that looks to be intended as docstring but accidentally
is just a normal comment.

Didn't create an issue as the readme said it's not neccessary for
trivial changes.

## Test Plan

<!-- How was it tested? -->
Can be tested by regenerating the docs.

Co-authored-by: Marcus Näslund <vidaochmarcus@gmail.com>

crates/ruff_annotate_snippets/src/renderer/mod.rs

@@ -100,7 +100,7 @@ impl Renderer {
         self
     }
 
-    // Set the terminal width
+    /// Set the terminal width
     pub const fn term_width(mut self, term_width: usize) -> Self {
         self.term_width = term_width;
         self