Remove duplicate lines

Author: jetvolkov

docs/input/docs/learn/branching-strategies/index.cshtml

@@ -38,9 +38,6 @@ b5d142 -> 2.0.0+0 (2.0.0 branch was merged, so main is now at 2.0.0)
     <li><code>support/</code></li>
     <li><code>release/</code></li>
     <li>pull requests (stash, github and a few others)</li>
-    <li><code>main</code></li>
-    <li><code>main</code></li>
-    <li><code>main</code></li>
 </ul>
 
 <p>