doc: how to change the behaviour

While describing what's being done by default, best to mention how to
adapt that.

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

README.md

@@ -16,6 +16,7 @@ information (e.g. available remote addresses), available network
 interfaces, request new MPTCP subflows, handle requests for subflows,
 etc.
 
+## Behavior
 By default, this daemon will load the `addr_adv` plugin, which will
 add MPTCP endpoints with the `subflow` flag ("client" mode) for the
 default in-kernel path-manager. Note that this is something
@@ -28,6 +29,14 @@ userspace path-manager and a custom made
 [plugin](https://github.com/multipath-tcp/mptcpd/wiki/Plugins) using
 the [C API](https://mptcpd.mptcp.dev/doc/html/).
 
+To change this behavior, with NetworkManager, look for the
+`connection.mptcp-flags` option in the
+[settings](https://networkmanager.dev/docs/api/latest/nm-settings-nmcli.html#nm-settings-nmcli.property.connection.mptcp-flags),
+while for `mptcpd`, look at the `/etc/mptcpd/mptcpd.conf` config
+file, or disable the service if it is not needed. Make sure not to
+have both NetworkManager and `mptcpd` conflicting to configure the
+MPTCP endpoints.
+
 ## Installing `mptcpd`
 `mptcpd` is packaged in most major distributions:
 

mptcpd.dox

@@ -28,6 +28,14 @@
  * [plugin](https://github.com/multipath-tcp/mptcpd/wiki/Plugins) using
  * the C API that is described here.
  *
+ * To change this behavior, with NetworkManager, look for the
+ * `connection.mptcp-flags` option in the
+ * [settings](https://networkmanager.dev/docs/api/latest/nm-settings-nmcli.html#nm-settings-nmcli.property.connection.mptcp-flags),
+ * while for `mptcpd`, look at the `/etc/mptcpd/mptcpd.conf` config
+ * file, or disable the service if it is not needed. Make sure not to
+ * have both NetworkManager and `mptcpd` conflicting to configure the
+ * MPTCP endpoints.
+ *
  * @see Additional higher level documentation is available in the
  *      [`mptcpd` Wiki](https://github.com/multipath-tcp/mptcpd/wiki/Plugins).
  */