docs: add homepage banner in support of Ukraine (#6811)

* Adding social banner in support of Ukraine

* Adding flag to the banner

* Updating donation URL

* Updating URL for the fundraiser

website/src/pages/index.tsx

@@ -238,6 +238,15 @@ export default function Home(): JSX.Element {
   return (
     <Layout title={tagline} description={description}>
       <main>
+        <div>
+          <div className={styles.banner}>
+            Support Ukraine 🇺🇦{' '}
+            <Link to="https://opensource.facebook.com/support-ukraine">
+              Help Provide Humanitarian Aid to Ukraine
+            </Link>
+            .
+          </div>
+        </div>
         <HeroBanner />
         <MigrationAnnouncement />
         <div className={styles.section}>

website/src/pages/styles.module.css

@@ -49,6 +49,15 @@
   max-width: 768px;
 }
 
+.banner {
+  font-weight: bold;
+  font-size: 20px;
+  padding: 20px;
+  max-width: 768px;
+  margin: 0 auto;
+  text-align: center;
+}
+
 .hero {
   background-color: #2b3137;
   padding: 48px;