man pages on zpool-add and zpool-attach

[gYxjuTyK]

Suggestion: add some warning text in the man pages of zpool-add and zpool-attach :
NOTE: add is NOT the same as attach ! add will extend the capacity of the pool. If you want to create a mirror of your only rpool use attach instead.
NOTE: attach is NOT the same as add ! attach will create a mirror while add will extend the capacity of the pool.
usage example: zpool attach rpool /dev/disk/by-id/disk1 /dev/disk/by-id/disk2

I could not (back in 2019 on FreeBSD) easily recover (de-add/remove) from an add'd capacity because I kept getting error messages.
It's easy to confuse them so I thought it would be a good idea with some documentation ?

[amotin]

Are you saying that somebody who actually read the present man pages could be confused? Adding more scary notes to the document that is not being read may not help, but actually produce the opposite result. But if you see some better possible wording for existing text without bloating it, please open a PR.