Correct text in starter.ss regarding depletion settings

[k-doering-NOAA]

What issue(s) does this PR address?

(note: including the keyword "resolves" means the issue will be closed automatically when merged in.)
This changes the depletion setting line in starter.ss_new to read SPBvirgin instead of SPB0 for option 1, which clarifies that the virgin biomass is used and not unfished biomass.

Link issue(s), replacing everything in [ ]: n/a

Describe the issue, if not included in the PR

What tests have been done? Upload any model input files created for testing in a zip file, if possible.

n/a

What tests/review still need to be done? Who can do it, and by when is it needed (ideally)?

n/a

Check which is true. This PR requires:

• no further changes to r4ss
• no further changes to the manual
• no further changes to SSI (the SS3 GUI)
• no further changes to the stock synthesis change log (new features, bug reports)

Describe any changes in r4ss/SS3 manual/SSI that are needed (if not checked):

Change the wording in the manual

If changes are needed in the change log, please fill in the table here:

Version	Date	Description	Issue	Input change	Action	Topic	Type
3.30.20	[Add date]	[add concise description]	#[add issue]	[yes or no]	[fix, new, or revise]	[e.g., biology. Use issue label options.]	[input, output, and/or calc, or ALL]

Additional information (optional):

[Rick-Methot-NOAA]

good fix