docs: Add rustdoc comments for functions, structs, and traits

Co-authored-by: aider (openai/andrew/openrouter/sonoma-sky-alpha) <aider@aider.chat>

src/filter_plugin/head.rs

@@ -14,6 +14,10 @@ impl HeadBytesFilter {
     /// # Arguments
     ///
     /// * `count` - The maximum number of bytes to read from the input.
+    ///
+    /// # Returns
+    ///
+    /// A new instance of `HeadBytesFilter`.
     pub fn new(count: usize) -> Self {
         Self {
             remaining: count,
@@ -88,6 +92,10 @@ impl HeadLinesFilter {
     /// # Arguments
     ///
     /// * `count` - The maximum number of lines to read from the input.
+    ///
+    /// # Returns
+    ///
+    /// A new instance of `HeadLinesFilter`.
     pub fn new(count: usize) -> Self {
         Self {
             remaining: count,