v1.2.0 Documentation is all

Add significant documentation to the package

• Added mini-vignettes pertaining to CFB Data functionality:

  • cfbd_betting,
  • cfbd_games,
  • cfbd_plays,
  • cfbd_recruiting,
  • cfbd_stats,
  • cfbd_teams

• Introductory vignette stub added

ESPN/CFBD metrics function variable return standardization

• Change id variable to team_id in espn_ratings_fpi()
• Changed espn_game_id variable to game_id in espn_metrics_wp(), corrected the away_win_percentage calculation and added tie_percentage to the returns.
• Change id variable to athlete_id in cfbd_metrics_ppa_players_season()