change typo in docs/docs/concepts/protocol

/08-fees.mdx
 from broker free to broker fee

docs/concepts/protocol/08-fees.mdx

@@ -8,7 +8,7 @@ import Link from "@docusaurus/Link";
 import { links } from "@site/src/constants";
 
 The Sablier Protocol is entirely free to use. There is no protocol fee. However, external integrators who manage their
-own UI may charge broker free in exchange for providing their services. Broker fees can only be charged when a stream is
+own UI may charge broker fee in exchange for providing their services. Broker fees can only be charged when a stream is
 created, and is capped at 10%.
 
 ## Broker fees