Update Richards vignette: parameters, fig width, eqnarray

[arni-magnusson]

Minor edits in Richards growth vignette, see
nmfs-ost/ss3-doc#265 (comment)

[arni-magnusson]

Thank you for your help. I'm not quite sure where the \\ should go, can you elaborate?
The attached screenshot highlights the \\[4ex] that I used to end lines in the equation array, along with the resulting output when I render it in quarto, which seems to look fine.

The tradition in eqnarray seems to be to not end the final line with a \\. Is that the one you're referring to? Happy to tweak these line endings as needed - also feel free to commit those changes if that's easier.

[e-perl-NOAA]

Nevermind @arni-magnusson, I see it working now. My quarto was just rendering things incorrectly the first time (where all of those equations were on the same line). It has now rendered correctly