[doc] Add default and optional values for arguments in documentation

[sbreitbart-NOAA]

Add default and optional values for arguments in documentation as per #256

[github-actions]

New version checklist

• Package version in DESCRIPTION has been updated
• Release notes have been drafted/published
• Cheatsheet content has been updated (if applicable)
• Cheatsheet version has been updated

[github-actions]

Code Metrics Report

Coverage	Code to Test Ratio	Test Execution Time
66.2%	1:0.1	5m26s

Code coverage of files in pull request scope (67.3%)

Files	Coverage
R/add_theme.R	74.1%
R/convert_output.R	50.4%
R/html_all_figs_tables.R	0.0%
R/plot_abundance_at_age.R	83.5%
R/plot_biomass.R	83.4%
R/plot_biomass_at_age.R	83.7%
R/plot_catch_comp.R	85.7%
R/plot_indices.R	92.9%
R/plot_landings.R	97.3%
R/plot_recruitment.R	80.4%
R/plot_spawning_biomass.R	72.8%
R/plot_stock_recruitment.R	99.2%
R/process_data.R	55.7%
R/save_all_plots.R	75.0%
R/table_landings.R	95.3%
R/theme_noaa.R	65.6%
R/utils_plot.R	85.9%
R/utils_rda.R	88.0%
R/utils_table.R	71.0%

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Reported by octocov

[Schiano-NOAA]

Thanks for doing this! It generally looks good. Only change that needs to be made is that scale_amount for I believe all functions is a numeric value and the default should be 1 not "1"

Also in regards to your comment in #264, instead of rebasing that branch to this one, I think we should just mege this one when it's finished then I can rebase to main on the other branch