Removed hardcoded subnetwork value.

apps/block_scout_web/lib/block_scout_web/templates/layout/_topnav.html.eex

@@ -16,7 +16,7 @@
          <span class="nav-link-icon">
          <svg xmlns="http://www.w3.org/2000/svg" width="6" height="6">
          <circle cx="3" cy="3" r="3" fill="#80d6a1"></circle>
-         </svg> </span>Sokol Testnet</a>
+         </svg> </span><%= subnetwork_title() %></a>
      <button class="new-button" id="dark-mode-changer">
         <svg xmlns="http://www.w3.org/2000/svg" width="15" height="16">
             <path fill="#a3a9b5" fill-rule="evenodd" d="M14.88 11.578a.544.544 0 0 0-.599-.166 5.7 5.7 0 0 1-1.924.321c-3.259 0-5.91-2.632-5.91-5.866 0-1.947.968-3.759 2.59-4.849a.534.534 0 0 0-.225-.97A5.289 5.289 0 0 0 8.059 0C3.615 0 0 3.588 0 8s3.615 8 8.059 8c2.82 0 5.386-1.423 6.862-3.806a.533.533 0 0 0-.041-.616z"></path>