Fix typos in documentation

docs/api/middleware.md

@@ -110,7 +110,7 @@ class DemoMiddleware
     $app->get('/user', DemoMiddleware::class, UserController::class);
     ```
 
-This highlights how middleware classes provide the exact same functionaly as using inline functions,
+This highlights how middleware classes provide the exact same functionality as using inline functions,
 yet provide a cleaner and more reusable structure.
 Accordingly, all examples below use middleware classes as the recommended style.
 

docs/async/promises.md

@@ -189,7 +189,7 @@ you'll end up using promises one way or another no matter what.
 
 The major feature is that this means that anything that takes some time will
 no longer block the entire execution.
-These non-blocking operations are especially benefitial for anything that incurs
+These non-blocking operations are especially beneficial for anything that incurs
 some kind of <abbrev title="Input/Output">I/O</abbrev>, such as
 [database queries](../integrations/database.md), HTTP API requests,
 [filesystem access](../integrations/filesystem.md) and much more.

src/FilesystemHandler.php

@@ -103,7 +103,7 @@ public function __invoke(ServerRequestInterface $request): ResponseInterface
             }
 
             // Assign MIME type based on file extension (same as nginx/Apache) or fall back to given default otherwise.
-            // Browers are pretty good at figuring out the correct type if no charset attribute is given.
+            // Browsers are pretty good at figuring out the correct type if no charset attribute is given.
             $ext = \strtolower(\substr($path, \strrpos($path, '.') + 1));
             $headers = [
                 'Content-Type' => $this->mimetypes[$ext] ?? $this->defaultMimetype