A plugin API that allows customizing existing topic-backed static pages, like:
faq, tos, privacy (see: StaticController) The block passed to this
method has to return a SiteSetting name that contains a topic id.
```
add_topic_static_page("faq") do |controller|
current_user&.locale == "pl" ? "polish_faq_topic_id" : "faq_topic_id"
end
```
You can also add new pages in a plugin, but remember to add a route,
for example:
```
get "contact" => "static#show", id: "contact"
```