lagg.4: note laggtype arg and reorder wireless example

[ceri]

Summary

The wireless example in lagg(4)'s manpage no longer works.

laggtype is not documented in the manpage other than in the example, so add a paragraph about it.

While here, move the section on rc.conf to a plan where it sits more logically.

[pauamma_gundo.com]

share/man/man4/lagg.4

198

Because some WiFi interfaces won't allow setting the MAC address, the recommended procedure is now to set the Ethernet interface's address to the WiFi's. See example 3 in https://docs.freebsd.org/en/books/handbook/advanced-networking/#network-aggregation.

[rgrimes]

share/man/man4/lagg.4

197

I would move the "up" to the line setting the ethernet MAC, just slightly cleaner to have the MAC set before the interface comes up.