Add docs and fix docs

lib/WebDriver/Session.php

@@ -33,7 +33,6 @@
  * @method void doubleclick() Double-clicks at the current mouse coordinates (set by moveto).
  * @method array execute_sql($jsonQuery) Execute SQL.
  * @method array execute_async($jsonScript) Inject a snippet of JavaScript into the page for execution in the context of the currently selected frame.
- * @method string file($jsonFile) Upload file.
  * @method void forward() Navigates forward in the browser history, if possible.
  * @method void keys($jsonKeys) Send a sequence of key strokes to the active element.
  * @method array getLocation() Get the current geo location.
@@ -570,7 +569,9 @@ protected function getIdentifierPath($identifier)
     public function file($arguments)
     {
         // Since Selenium 4.17 the file URL has been prefixed with /se because
-        // it is not a W3C command.
+        // it is not a W3C command. See
+        // https://github.com/w3c/webdriver/issues/1355 for discussions about
+        // the W3C spec and file uploads.
         if ($this->isW3C()) {
             try {
                 $result = $this->curl('POST', '/se/file', $arguments);