docs: fix section title

kenjis · kenjis · commit def452d60c13 · 2022-11-30T09:44:50.000+09:00
diff --git a/user_guide_src/source/incoming/controllers.rst b/user_guide_src/source/incoming/controllers.rst
@@ -79,7 +79,7 @@ modify this by passing the duration (in seconds) as the first parameter:
 
 .. _controller-validate:
 
-Validating data
+Validating Data
 ***************
 
 $this->validate()
