(Minor) Update rest-client.adoc

Minor correction to the `ResteasyReactiveClientRequestFilter` code snippet - corrected the type of the parameter `requestContext` in the method `filter`.

Author: njlbenn

docs/src/main/asciidoc/rest-client.adoc

@@ -1334,7 +1334,7 @@ Alternatively, you can implement the `ResteasyReactiveClientRequestFilter` inter
 public class TestClientRequestFilter implements ResteasyReactiveClientRequestFilter {
 
     @Override
-    public void filter(ResteasyReactiveClientRequestFilter requestContext) {
+    public void filter(ResteasyReactiveClientRequestContext requestContext) {
         Providers providers = requestContext.getProviders();
         // ...
     }