docs: update subtitle sudheerj#67 to match content

Author: kenshanta

README.md

@@ -2087,7 +2087,7 @@ class ParentComponent extends React.Component {
 
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-67. ### Why you can't update props in React?
+67. ### Why can't you update props in React?
 
     The React philosophy is that props should be _immutable_(read only) and _top-down_. This means that a parent can send any prop values to a child, but the child can't modify received props.