add/document dictionary improvement for load_rosters()$status

[tanho63]

c/o @john-b-edwards in discord

status_description_abbr is an abbreviated representation of the status column. it's fairly trivial to see what each acronym refers to using both columns:

nflreadr::load_rosters(2022) |>
    dplyr::group_by(status_description_abbr, status) |>
    dplyr::summarise(.groups="drop") |>
    print(n=21)
#> # A tibble: 21 × 2
#>    status_description_abbr status         
#>    <chr>                   <chr>          
#>  1 A01                     Active         
#>  2 E02                     Ex/Comm. Perm. 
#>  3 P01                     Practice Squad 
#>  4 P02                     Prac Sq.; Inj  
#>  5 P03                     Int'l PSquad   
#>  6 P06                     PS; Exc        
#>  7 P07                     PS; Vet        
#>  8 R01                     R/Injured      
#>  9 R02                     R/Retired      
#> 10 R03                     R/DNR          
#> 11 R04                     R/PUP          
#> 12 R05                     R/NFIN         
#> 13 R06                     R/Left Squad   
#> 14 R23                     Reserve/Future 
#> 15 R27                     R/NFIL         
#> 16 R30                     R/Com Sus-1 Yr 
#> 17 R33                     R/Club Susp.   
#> 18 R40                     R/Susp < 1Yr   
#> 19 R47                     R/NFIN; DFR    
#> 20 R48                     R/Injured; DFR 
#> 21 W03                    Waivers/No Rec.