add note to mission continue page

[Hwurzburg]

addresses #6490

[rmackay9]

Thanks for this although I think it's more likely that a user would set the home position from the GCS rather than adding a set-home command to the mission. Mission Planner doesn't even display the do-set-home mission command. Anyway, maybe I'll add a PR to fixup the wording and perhaps provide a link back to a user wiki page which shows how to set home

[Hwurzburg]

Actually Mission Planner does indeed display DO_SET_HOME as a mission command, at least in Plane. But explaining that home can be set persistently thru disarms, either by right click context menu or mission commands would be a good addition under Mission Planning tab