Avoid an unnecessary collect into a Vec

Summary: Simplify and avoid additional memory.

Reviewed By: perehonchuk

Differential Revision: D59218144

fbshipit-source-id: 643cf4ecc5217775401ec20aac8ea416b4625502

starlark-rust/starlark/src/docs/markdown.rs

@@ -137,10 +137,8 @@ fn render_function_parameters(params: &[DocParam]) -> Option<String> {
 
             let mut lines_iter = docs.lines();
             if let Some(first_line) = lines_iter.next() {
-                let rest_of_lines: Vec<&str> = lines_iter.collect();
-
                 let _ = writeln!(output, "* `{name}`: {first_line}");
-                for line in &rest_of_lines {
+                for line in lines_iter {
                     let _ = writeln!(output, "  {line}");
                 }
             } else {