more docs

actix-files/src/files.rs

@@ -162,8 +162,25 @@ impl Files {
 
     /// Sets path filtering closure.
     ///
-    /// When a path doen't pass the filter, [`Files::default_handler`] is called if set, otherwise,
+    /// The path provided to the closure is relative to `serve_from` path.
+    /// You can safely join this path with the `serve_from` path to get the real path.
+    /// However, the real path may not exist since the filter is called before checking path existence.
+    ///
+    /// When a path doesn't pass the filter, [`Files::default_handler`] is called if set, otherwise,
     /// `404 NotFound` is returned.
+    /// ```
+    /// use std::path::Path;
+    /// use actix_files::Files;
+    ///
+    /// let files_service = Files::new("/", "./static").path_filter(|path, _| {
+    ///     path.components.count() == 1
+    ///         && Path::new("./static")
+    ///             .join(path)
+    ///             .symlink_metadata()
+    ///             .map(|m| m.file_type().is_symlink())
+    ///             .unwrap_or(false)
+    /// });
+    /// ```
     pub fn path_filter<F>(mut self, f: F) -> Self
     where
         F: Fn(&Path, &RequestHead) -> bool + 'static,