Update Tournament readme with more details

Based on the conversation here:
exercism/rust#122

This addresses a few problems that @ijanos had

- What do the column headers mean?
- How are points awarded?
- What is the input format?

There's still a need for a default test json file, but that can come in
a different PR.

Author: whit0694

tournament.md

@@ -1,15 +1,66 @@
 Tally the results of a small football competition. Based on an input file
-containing which team played against which and what the outcome was 
+containing which team played against which and what the outcome was
 create a file with a table like this:
 
 ```
 Team                           | MP |  W |  D |  L |  P
 Devastating Donkeys            |  3 |  2 |  1 |  0 |  7
-Allegoric Alaskians            |  3 |  2 |  0 |  1 |  6
+Allegoric Alaskans             |  3 |  2 |  0 |  1 |  6
 Blithering Badgers             |  3 |  1 |  0 |  2 |  3
 Courageous Californians        |  3 |  0 |  1 |  2 |  1
 ```
 
-The outcome should be ordered by points, descending. To keep things simple ties
-are broken by looking at the number of wins and if that doesn't solve anything
-by ordering the team names alphabetically.
+What do those abbreviations mean?
+
+- MP: Matches Played
+- W: Matches Won
+- D: Matches Drawn (Tied)
+- L: Matches Lost
+- P: Points
+
+A win earns a team 3 points. A draw earns 1. A loss earns 0.
+
+The outcome should be ordered by points, descending. Ties are broken by
+first looking at the number of wins then by ordering the team names
+alphabetically.
+
+###
+
+Input
+
+Your tallying program will receive input that looks like:
+
+```
+Allegoric Alaskans;Blithering Badgers;win
+Devastating Donkeys;Courageous Californians;draw
+Devastating Donkeys;Allegoric Alaskans;win
+Courageous Californians;Blithering Badgers;loss
+Blithering Badgers;Devastating Donkeys;loss
+Allegoric Alaskans;Courageous Californians;win
+```
+
+The result of the match refers to the first team listed. So this line
+
+```
+Allegoric Alaskans;Blithering Badgers;win
+```
+
+Means that the Allegoric Alaskans beat the Blithering Badgers.
+
+This line:
+
+```
+Courageous Californians;Blithering Badgers;loss
+```
+
+Means that the Blithering Badgers beat the Courageous Californians.
+
+And this line:
+
+```
+Devastating Donkeys;Courageous Californians;draw
+```
+
+Means that the Devastating Donkeys and Courageous Californians tied.
+
+Your program should only accept inputs that follow this format.