Rework the contribute/get involved section to match the mock-up

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

src/_sass/_custom.scss

@@ -105,6 +105,13 @@ body {
   margin-bottom: auto;
 }
 
+#contribute .feature__item {
+  @media (min-width: 37.5em) {
+    width: 45%;
+    margin-inline-start: 3.3%;
+  }
+}
+
 #blog {
   margin-top: 2em;
   background-color: #eee;

src/index.html

@@ -14,7 +14,7 @@ excerpt: >-
   Even if some of the servers fail or are taken over by an attacker,
   the entire file store continues to function correctly, preserving your privacy and security.
 documentation:
-  - title: "Documentation"
+  - title: "Official Documentation"
 documentation_list:
   - image_path: /assets/images/overview.svg
     alt: "overview"
@@ -37,8 +37,11 @@ documentation_list:
       <li><a href="https://tahoe-lafs.org/trac/tahoe-lafs/wiki/FAQ">Frequently Asked Questions</a></li>
     </ul>'
 contribute:
-  - title: "Contribute"
-    excerpt: ""
+  - title: "Get Involved"
+    excerpt: '
+      Interested in learning more or wanting to contribute to Tahoe-LAFS?<br/>
+      There are various ways to get involved!
+    '
 contribute_list:
   - image_path: /assets/images/discussions.svg
     alt: "discussions"
@@ -48,12 +51,20 @@ contribute_list:
       <li>Join the <a href="https://libera.chat/" target="_blank"><b>#tahoe-lafs</b></a> channel on Libera</li>
       <li>Meet us on <a href="https://meet.jit.si/AccurateFiltersManipulateBefore" target="blank"><b>Tuesday</b></a> at 17:00 UTC on Jitsi </li>
     </ul>'
+  - image_path: /assets/images/collaborations.svg
+    alt: "collaborations"
+    title: "Collaborations"
+    excerpt: >-
+      <ul>
+      <li><a href="https://leastauthority.com/" target="_blank">Least Authority</a> uses and contributes to Tahoe-LAFS</li>
+      <li>Google, Inc. sponsored Tahoe-LAFS through its Summer of Code program in 2010 and 2013</li>
+      </ul>
   - image_path: /assets/images/issues.svg
     alt: "issues"
     title: "Issues"
     excerpt: '<ul>
-      <li>Visit the <a href="https://code.lafs.eval.latfa.net/tahoe-lafs/trac/issues"><b>issue</b></a> tracker</li>
-      <li>Register an <a href="https://code.lafs.eval.latfa.net/user/sign_up"><b>account</b></a> to interact</li>
+      <li>Visit the <a href="https://forge.lafs.eval.latfa.net/tahoe-lafs/trac"><b>issue</b></a> tracker</li>
+      <li>Register an <a href="https://forge.lafs.eval.latfa.net/user/sign_up"><b>account</b></a> to interact</li>
     </ul>'
   - image_path: /assets/images/code.svg
     alt: "code"
@@ -74,6 +85,9 @@ about:
       and maintained by a group of hardy volunteers.
       We are grateful for their energy, expertise, and support.
       Check out some of the main contributors to this project!
+    url: "https://tahoe-lafs.org/trac/tahoe-lafs/wiki/AboutUs"
+    btn_label: "Our Contributors"
+    btn_class: "btn--primary"
 ---
 <div id="documentation">
 {% include feature_row id="documentation" type="center" %}
@@ -85,6 +99,7 @@ about:
 {% include feature_row id="contribute_list" %}
 </div>
 
+<br/>
 <div id="blog">
 {% include feature_row id="blog" type="center" %}
 <div class="entries-grid">