Git force add data/ss3/synoptic-maturity-age.csv + maturity code

[seananderson]

https://github.com/pbs-assess/dogfish-assess/blob/main/ss3/01-outside-stock-synthesis-data.R#L426

Also, clarify the source of the .csv and the resulting figure 'mat-lit-with-synoptic.png'. Is this based on the 55 or 77 cutoff in Figure 16?

[quang-huynh]

Figure 15 uses female code 77 from Figure 16. Code 55 is never used outside Figure 16.