fix: /https/settings shows the https section and switches https.acme_staging, for the Router Manager.

README.md

@@ -1018,7 +1018,7 @@ curl http://10.0.0.4:7081/status
 
 ### Tokens and signing in
 
-`/config`, `/metrics/history`, `/metrics/settings`, `/users`, `/service-accounts`, `/groups`, `/site-to-site`, `/backup`, `/remote-access`, `/ca`, `/logs`, `/sites`, `/dns`, `/shell` and `/account` need a JWT in an `Authorization: Bearer` header, signed with
+`/config`, `/metrics/history`, `/metrics/settings`, `/https/settings`, `/users`, `/service-accounts`, `/groups`, `/site-to-site`, `/backup`, `/remote-access`, `/ca`, `/logs`, `/sites`, `/dns`, `/shell` and `/account` need a JWT in an `Authorization: Bearer` header, signed with
 HS256 by the key the web service makes on its first run, `/etc/vpn-router/web.key` (root only).
 The key never leaves the router; while it does not exist these paths and `/auth` are not served
 (404). A missing, expired or wrongly signed token, or one of another algorithm, gets 401 with
@@ -1405,6 +1405,18 @@ A change is made, checked and applied as for `/site-to-site`.
 
 A change is made, checked and applied as for `/site-to-site`.
 
+### The /https/settings API
+
+`/https/settings` shows the settings of HTTPS and changes the CA of Caddy's certificates, with the
+same token as `/users`.
+
+| Request | Body | Answer |
+| --- | --- | --- |
+| `GET /https/settings` | | `{"settings"}`: the `https` section |
+| `PUT /https/settings` | `{"acme_staging"}`; any other setting of the `https` section is 400, as it is changed on the router with `vpn-config-edit` | `{"settings"}` |
+
+A change is made, checked and applied as for `/site-to-site`.
+
 ### The /remote-access API
 
 `/remote-access` shows and changes the remote access systems, IKEv2 (`p2s`),
@@ -1484,6 +1496,9 @@ obtains from an ACME CA, those of the web sites with `tls` `acme` included.
 vpn-config-edit set --restart https.acme_staging true
 ```
 
+The Router Manager switches it on the Overview, and `PUT /https/settings` changes it (see The
+/https/settings API).
+
 `vpn-router-setup` writes Caddy's configuration to `/etc/caddy/vpn-router.Caddyfile` (root, group
 `caddy`, the group Caddy runs as, mode 0640), which the
 package's drop-in `/usr/lib/systemd/system/caddy.service.d/vpn-router.conf` makes `caddy.service`