Better template documentation

README.md

@@ -34,12 +34,33 @@ A less sane, but better for testing version can be found in [echoip_test.toml](e
 
 Templates in the templates folder exist for every rich page that `echoip-slatecave` supports.
 
-The code that rendeers them can be found in [src/templating_engine.rs](src/templating_engine.rs).
-
 There is a configuration file for templates which by default is the `extra.toml` file in the template directory. Its content is exposed to the templates in the `extra` struct.
 
 The default templates should make use of everything exposed to the templating part, the `data.result` or `data` object is usually what you get when you ask for the json version.
 
+In addition to that the following fields are accessible from inside the template:
+
+`view`
+: The views name (the basename of the template file, i.e. `404` or `ip`)
+
+`format`
+: The format name (`html`, `text`, `json`)
+
+`mimetype`
+: The resulting mimetype (i.e. `text/plain; charset=utf-8`)
+
+`http_status`
+: The numeric HTTP Status-Code at the time of rendering the template.
+
+`language`
+: The language requested by the browser.
+
+`dns_resolvers`
+: A list of [Selectable](src/settings.rs) structs representing the available DNS-Resolvers.
+
+`dns_resolver_id`
+: The id of the currently selected DNS-Resolver
+
 The templates are covered by the AGPL as well, please share them with your users if you modified them.
 
 ### GeoLite2 database