docs(usage): fix wrong component example

Author: jsun969

README.md

@@ -14,7 +14,7 @@
 npm install @hookform/devtools -D
 ```
 
-3. Add `<Devtool control={control}>` in your code  
+3. Add `<Devtool control={control} />` in your code  
    _This won't show devtools component anymore! Just for extension detect your form_
 4. Enjoy!