Add smaller nfl file, column descriptions

Author: jayb

Diff for: mlb-elo/README.md

@@ -5,7 +5,7 @@ files:
 ---
 # MLB Elo
 
-This file contains links to the data behind [The Complete History Of MLB](https://projects.fivethirtyeight.com/complete-history-of-mlb/) and our [MLB Predictions](https://projects.fivethirtyeight.com/2018-mlb-predictions/).
+This file contains links to the data behind [The Complete History Of MLB](https://projects.fivethirtyeight.com/complete-history-of-mlb/) and our [MLB Predictions](https://projects.fivethirtyeight.com/2019-mlb-predictions/).
 
 `mlb_elo.csv` contains game-by-game Elo ratings and forecasts back to 1871.
 `mlb_elo_latest.csv` contains game-by-game Elo ratings and forecasts for only the latest season.

Diff for: nba-carmelo/README.md

@@ -5,7 +5,7 @@ files:
 ---
 # NBA Elo
 
-This file contains links to the data behind [The Complete History Of The NBA](https://projects.fivethirtyeight.com/complete-history-of-the-nba/) and our [NBA Predictions](https://projects.fivethirtyeight.com/2018-nba-predictions/).
+This file contains links to the data behind [The Complete History Of The NBA](https://projects.fivethirtyeight.com/complete-history-of-the-nba/) and our [NBA Predictions](https://projects.fivethirtyeight.com/2020-nba-predictions/).
 
 `nba_elo.csv` contains game-by-game Elo ratings and forecasts back to 1946.
 `nba_elo_latest.csv` contains game-by-game Elo ratings and forecasts for only the latest season.

Diff for: nfl-elo/README.md

@@ -1,9 +1,44 @@
 ---
 files:
   - https://projects.fivethirtyeight.com/nfl-api/nfl_elo.csv
+  - https://projects.fivethirtyeight.com/nfl-api/nfl_elo_latest.csv
 ---
 # NFL Elo
 
-This file contains links to the data behind [The Complete History Of The NFL](https://projects.fivethirtyeight.com/complete-history-of-the-nfl/) and our [NFL Predictions](https://projects.fivethirtyeight.com/2017-nfl-predictions/).
+This file contains links to the data behind [The Complete History Of The NFL](https://projects.fivethirtyeight.com/complete-history-of-the-nfl/) and our [NFL Predictions](https://projects.fivethirtyeight.com/2019-nfl-predictions/).
 
 `nfl_elo.csv` contains game-by-game Elo ratings and forecasts back to 1920.
+`nfl_elo_latest.csv` contains game-by-game Elo ratings and forecasts for only the latest season.
+
+Column | Definition
+-----| ---------
+date | Date of game
+season | Year of season
+neutral | Whether game was on a neutral site
+playoff | Whether game was in playoffs, and the playoff round if so
+team1 | Abbreviation for home team
+team2 | Abbreviation for away team
+elo1_pre | Home team's Elo rating before the game
+elo2_pre | Away team's Elo rating before the game
+elo_prob1 | Home team's probability of winning according to Elo ratings
+elo_prob2 | Away team's probability of winning according to Elo ratings
+elo1_post | Home team's Elo rating after the game
+elo2_post | Away team's Elo rating after the game
+qbelo1_pre | Home team's quarterback-adjusted base rating before the game
+qbelo2_pre | Away team's quarterback-adjusted base rating before the game
+qb1 | Name of home starting quarterback
+qb2 | Name of away starting quarterback
+qb1_value_pre | Home starting quarterbacks's raw Elo value before the game
+qb2_value_pre | Away starting quarterbacks's raw Elo value before the game
+qb1_adj | Home starting quarterbacks's Elo adjustment for the game
+qb2_adj | Away starting quarterbacks's Elo adjustment for the game
+qb_elo_prob1 | Home team's probability of winning according to quarterback-adjusted Elo
+qb_elo_prob2 | Away team's probability of winning according to quarterback-adjusted Elo
+qb1_game_value | Home quarterback's Elo value during this game
+qb2_game_value | Away quarterback's Elo value during this game
+qb1_value_post | Home starting quarterbacks's raw Elo value after the game
+qb2_value_post | Away starting quarterbacks's raw Elo value after the game
+qbelo1_post | Home team's quarterback-adjusted base rating after the game
+qbelo2_post | Away team's quarterback-adjusted base rating after the game
+score1 | Home team's score
+score2 | Away team's score