chore: update references to reflect application name change to DevHub

- Changed the live application link in README.md to point to the new URL.
- Updated the repository name in the Contact page to match the new branding.
- Revised comments in the JSON Viewer component to align with the updated application name.

src/page/contact/index.tsx

@@ -5,7 +5,7 @@ import React from "react"
  */
 export default function Contact() {
   const owner = "onixbyte"
-  const repo = "json-visualiser"
+  const repo = "dev-hub"
 
   const handleRedirect = (e: React.FormEvent<HTMLFormElement>) => {
     e.preventDefault()