Add docs from gofiber/storage@d596831

Author: github-actions[bot]

docs/storage/redis/README.md

@@ -29,6 +29,7 @@ func (s *Storage) Delete(key string) error
 func (s *Storage) Reset() error
 func (s *Storage) Close() error
 func (s *Storage) Conn() redis.UniversalClient
+func (s *Storage) Keys() ([][]byte, error)
 ```
 ### Installation
 Redis is tested on the 2 last [Go versions](https://golang.org/dl/) with support for modules. So make sure to initialize one first if you didn't do that yet: