Add links to PHP Foundation with a Donate button (#821)

Co-authored-by: Derick Rethans <github@derickrethans.nl>
Co-authored-by: Lu Fei <52o@qq52o.cn>

Author: 3 people

index.php

@@ -200,6 +200,13 @@
 
 $SIDEBAR = <<<SIDEBAR_DATA
 
+    <div class='panel'>
+      <a href='https://thephp.foundation/' class='headline'>The PHP Foundation</a>
+      <div class='body'>
+        <p>The PHP Foundation is a collective of people and organizations, united in the mission to ensure the long-term prosperity of the PHP language.
+        <p><a href='https://thephp.foundation/donate/' class='btn btn-primary'>Donate</a></p>
+      </div>
+    </div>
 $announcements
     <p class='panel'><a href='/cal.php'>User Group Events</a></p>
     <p class='panel'><a href='/thanks.php'>Special Thanks</a></p>

styles/home.css

@@ -194,3 +194,25 @@ aside.tips .social-media .icon-twitter {
     font-size: 1.5em;
     vertical-align: middle;
 }
+
+/* Unheroic button */
+.btn {
+  box-sizing: border-box;
+  padding: 0.5rem 1rem;
+  margin-bottom: 1rem;
+  border-radius: 2rem;
+  text-align: center;
+  display: inline-block;
+  border: none;
+  transition: background-color 0.2s;
+}
+
+.btn-primary {
+  background-color: var(--dark-blue-color);
+  color: #fff !important;
+}
+
+.btn-primary:hover, .hero-btn-primary:focus {
+  background-color: var(--dark-magenta-color) !important;
+  border-color: var(--dark-magenta-color) !important;
+}