Remove subdomain and tld which are not required

app/views/admin/application_settings/_plantuml.html.haml

@@ -18,7 +18,7 @@
             = f.label :plantuml_enabled, _('Enable PlantUML'), class: 'form-check-label'
         .form-group
           = f.label :plantuml_url, 'PlantUML URL', class: 'label-bold'
-          = f.text_field :plantuml_url, class: 'form-control', placeholder: 'http://gitlab.your-plantuml-instance.com:8080'
+          = f.text_field :plantuml_url, class: 'form-control', placeholder: 'http://your-plantuml-instance:8080'
           .form-text.text-muted
             Allow rendering of
             = link_to "PlantUML", "http://plantuml.com"