chore: improve startup message (#4401)

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Author: nijel

etc/nginx/errors/weblate-timeout.html

@@ -316,7 +316,7 @@
           <h1 class="section-title min-m">Weblate took too long to respond</h1>
           <div class="page-desc">
             <p>The application did not respond before the proxy timeout expired.</p>
-            <p>This can happen while the container is still finishing startup, but it can also indicate a temporary backend problem.</p>
+            <p>This can happen while the application is still finishing startup, but it can also indicate a temporary backend problem.</p>
             <p class="small">Try again in a little while. If the problem persists, check the backend service health.</p>
           </div>
         </div>