docs: fix missing `.Body` (#123)

diff --git a/docs/en/latest/getting-started.md b/docs/en/latest/getting-started.md
index df39430..5e295e2 100644
--- a/docs/en/latest/getting-started.md
+++ b/docs/en/latest/getting-started.md
@@ -129,7 +129,7 @@
 
 ```
 func (p *Say) RequestFilter(conf interface{}, w http.ResponseWriter, r pkgHTTP.Request) {
-	body := conf.(SayConf).
+	body := conf.(SayConf).Body
 	if len(body) == 0 {
 		return
 	}