docs: add method docblocks

Author: kenjis

src/Authentication/Authenticators/Session.php

@@ -347,13 +347,21 @@ private function getActionTypes(): array
         return $types;
     }
 
+    /**
+     * Checks if the user is currently in pending login state.
+     * They need to do an auth action.
+     */
     public function isPending(): bool
     {
         $this->checkUserState();
 
         return $this->userState === self::STATE_PENDING;
     }
 
+    /**
+     * Checks if the visitor is anonymous. The user's id is unknown.
+     * They are not logged in, are not in pending login state.
+     */
     public function isAnonymous(): bool
     {
         $this->checkUserState();