[Docs] Add new logo and open graph image (#2350)

## Motivation for the change, related issues

This pull request adds the new logo to the Documentation website and an
open graph image to be used when users share the documentation on social
media. The changes include the following items:
- New logo on the documentation header
- New open graph image
- New favicon
- Cleaning up unnecessary assets 

**New documentation header **
<img width="890" height="540" alt="Screenshot 2025-07-10 at 19 23 37"
src="https://github.com/user-attachments/assets/79fdc5db-0a99-40ac-a58b-0e5e7b22a356"
/>

** Previous header ** 
<img width="991" height="449" alt="Screenshot 2025-07-10 at 19 37 42"
src="https://github.com/user-attachments/assets/4326f419-dc5b-41df-9658-05240af13129"
/>

** New opengraph image**
<img width="1200" height="600" alt="playground-logo"
src="https://github.com/user-attachments/assets/df694c3d-ae6b-4462-9bad-1de0a3a8e30e"
/>

** Previous opengraph image **
<img width="352" height="117" alt="Screenshot 2025-07-10 at 19 27 03"
src="https://github.com/user-attachments/assets/ae35ad65-65ab-4106-bbef-1b3230b40373"
/>

#2349 

cc @adamziel

Author: fellyph

packages/docs/site/docusaurus.config.js

@@ -121,6 +121,7 @@ const config = {
 	themeConfig:
 		/** @type {import('@docusaurus/preset-classic').ThemeConfig} */
 		({
+			image: 'img/playground-social-logo.png',
 			algolia: {
 				appId: 'EKWQ08DUQS',
 				apiKey: '2fcab4cf2c3596e775de8c4ab1fa065e',
@@ -131,8 +132,8 @@ const config = {
 				title: 'WordPress Playground',
 				logo: {
 					alt: 'WordPress Playground',
-					src: 'img/wordpress.svg',
-					srcDark: 'img/wordpress-dark.svg',
+					src: 'img/playground-logo.svg',
+					srcDark: 'img/playground-logo-dark.svg',
 				},
 				items: [
 					{