Add documentation regarding multi-vhost

Author: mjsir911

tpl/help/domains.md

@@ -1,27 +1,14 @@
-GoatCounter doesn’t store the domain a pageview belongs to; if you add
-GoatCounter to several (sub)domains then there’s no way to distinguish between
-requests to `a.example.com/path` and `b.example.com/path` as they’re both
-recorded as `/path`.
+GoatCounter *does*, optionally, store the domain a pageview belongs to;
+If the log importer script is run with `$host` in the log format, or uses a
+format that includes that, such as `combined-vhost`, `common-vhost`, `bunny`.
 
-This might be improved at some point in the future; the options right now are:
+Currently, javascript api `count.js`, does not support doing this.
 
-1. Create a new site for every domain; this is a completely separate site which
-   has the same user, login, etc. You will need to use a different site for
-   every (sub)domain.
+To report a host via the raw API include the `host` field within the `hits` list, such as:
 
-2. If you want everything in a single overview then you can add the domain to
-   the path, instead of just sending the path:
-
-        <script>
-            window.goatcounter = {
-                path: function(p) { return location.host + p }
-            }
-        </script>
-        {{template "code" .}}
-
-   For subdomains it it might be more useful to just add the first domain label
-   instead of the full domain here, or perhaps just a short static string
-   identifying the source.
-
-
-Also see [setting the endpoint in JavaScript]({{.Base}}/code/modify#setting-the-endpoint-in-javascript-4).
+```
+curl -X POST "$api/count" \
+    -H 'Content-Type: application/json' \
+    -H "Authorization: Bearer $token" \
+    --data '{"no_sessions": true, "hits": [{"host": "example.org", "path": "/one"}]}'
+```