Refining a warning message

[k-doering-NOAA]

For this warning: https://github.com/nmfs-stock-synthesis/stock-synthesis/blob/7c4cbd501ae20cd5dca0fc8c18febd97324fde9f/SS_readdata_330.tpl#L529

I was wondering if a suggestion about what should be done should be added (e.g., add a really small value like 0.001 amount of catch) to help user figure out what to do if they run into it? I expect this warning will come up because there are many reasons there may be 0 catch in the last year (esp. in simulation studies).