Updated comment message (#26158)

a simple grammar fix.

Author: notEpsilon

packages/react/src/ReactElementValidator.js

@@ -6,7 +6,7 @@
  */
 
 /**
- * ReactElementValidator provides a wrapper around a element factory
+ * ReactElementValidator provides a wrapper around an element factory
  * which validates the props passed to the element. This is intended to be
  * used only in DEV and could be replaced by a static type checker for languages
  * that support it.