review selectivity static caveat for LBSPR and LBB

[bsnouffer]

I came across this static caveat in LBSPR that we definitely need to change:
"The method treats each year as an independent estimate, so changes in selectivity are less of a concern."

For LBSPR (and LBB), changes in selectivity across years may indicate recruitment (unless that change in selectivity actually occurred), which will lead to a bias in F and SPR.

Selectivity changes could therefore be a real concern.

-Jason

[bsnouffer]

Updated the caveat to: "The method treats each year as an independent estimate. Changes in selectivity across years may indicate recruitment events (unless that change in selectivity actually occurred), which may lead to a bias in estimates of F and SPR in this method."

Added the caveat to LBB as well (replacing SPR for B/B0)

Jason and I completed while working on the peer review comments. It has been updated in FishPath.