Add topics for Gists (#413)

templates/base/base_header.html

@@ -114,6 +114,7 @@
                                                         <p class="text-gray-400"><code class="text-slate-800 dark:text-slate-300 pr-1">filename:myfile.txt</code> {{ .locale.Tr "gist.search.help.filename" }}</p>
                                                         <p class="text-gray-400"><code class="text-slate-800 dark:text-slate-300 pr-1">extension:yml</code> {{ .locale.Tr "gist.search.help.extension" }}</p>
                                                         <p class="text-gray-400"><code class="text-slate-800 dark:text-slate-300 pr-1">language:go</code> {{ .locale.Tr "gist.search.help.language" }}</p>
+                                                        <p class="text-gray-400"><code class="text-slate-800 dark:text-slate-300 pr-1">topic:homelab</code> {{ .locale.Tr "gist.search.help.topic" }}</p>
                                                     </div>
                                                 </div>
                                             </div>