add search-url section to initial-setup.html template.

This section allows users to point this website to the Meilisearch instance
which provides the search features of this site.

templates/initial-setup.html

@@ -54,6 +54,21 @@
 
                     <hr>
 
+                    <label>Search URL</label>
+                    <p class="fr-gui-form-hint">
+                        This refers to the URL used by the seach instance this
+                        website calls out to for its search features. If you're
+                        running this on your local dev. machine, use
+                        <strong>http://localhost:7700</strong> (this is the
+                        default for port for Meilisearch.
+                    </p>
+                    <input required
+                           type="text"
+                           name="SEARCH-URL"
+                           placeholder="Enter the search URL here...">
+
+                    <hr>
+
                     <div class="be-gui-form-row">
 	                <input type="checkbox"
                                name="ALLOW-SIGN-UP"