Update mavros.md

[oponfil]

GPS setpoints can be sent via MAVROS

[okalachev]

It is still not supported using SET_POSITION_TARGET_GLOBAL_INT message (/mavros/setpoint_raw/global topic).

They just added another topic to mavros that emulates global setpoints using local setpoint messages.

So I believe this change is incorrect.

[oponfil]

In this case, you should change the link to another issue. Because the issue by the link is resolved.

[okalachev]

OK, for now the global position setpoints are actually supported.