Update favicon and app title (#4)

Part of [laconicd testnet validator enrollment](https://www.notion.so/laconicd-testnet-validator-enrollment-6fc1d3cafcc64fef8c5ed3affa27c675)

- Use laconic favicon and change app title
- Get wallet connect meta URL from `.env`

Co-authored-by: IshaVenikar <ishavenikar7@gmail.com>
Reviewed-on: cerc-io/testnet-onboarding-app#4

public/index.html

@@ -7,7 +7,7 @@
     <meta name="theme-color" content="#000000" />
     <meta
       name="description"
-      content="Web site created using create-react-app"
+      content="Testnet Onboarding App"
     />
     <link rel="apple-touch-icon" href="%PUBLIC_URL%/logo192.png" />
     <!--

public/manifest.json

@@ -1,6 +1,6 @@
 {
-  "short_name": "React App",
-  "name": "Create React App Sample",
+  "short_name": "Testnet Onboarding App",
+  "name": "Testnet Onboarding App",
   "icons": [
     {
       "src": "favicon.ico",