docs(marketing): replace em dash with colon in plan review description

For provenance purposes, this commit was AI assisted.

Author: backnotprop

apps/marketing/src/pages/index.astro

@@ -312,7 +312,7 @@ import AnnoReplace from '../components/landing/AnnoReplace.astro';
             <h3 class="cap-group-label">Commands</h3>
             <div class="cap-item">
               <span class="cap-name">Plan review</span>
-              <span class="cap-desc">Automatic — hooks into your agent's plan step</span>
+              <span class="cap-desc">Automatic: hooks into your agent's plan step</span>
             </div>
             <div class="cap-item">
               <code class="cap-cmd">/plannotator-annotate</code>