features: Add custom profile fields.

templates/zerver/features.html

@@ -240,6 +240,13 @@
                 Import an existing Slack or Gitter workspace into Zulip.
             </p>
         </div>
+        <div class="feature-block">
+            <h3>CUSTOM PROFILE FIELDS</h3>
+            <p>
+                Use Zulip to store directory information, links to social
+                media profiles, food preferences, or anything else.
+            </p>
+        </div>
         <div class="feature-block">
             <h3>YOUR FEATURE HERE</h3>
             <p>Zulip is open source, so if something important for