Update doc according to #109.

PiperOrigin-RevId: 279960897
Change-Id: Idec5b260b91dd1f63ba2d18857f4caf2db83255e

docs/contributing.md

@@ -142,10 +142,12 @@ release!). Contributions are certainly not limited to these suggestions!
 -   **General Games Wrapper**. There are several general game engine languages
     and databases of general games that currently exist, for example within the
     [general game-playing project](http://www.ggp.org/) and the
-    [Ludii General Game System](http://www.ludii.games/index.html) or [GAMUT](http://gamut.stanford.edu/) (a suite of normal-form game generators). A very nice
-    addition to OpenSpiel would be a game that interprets games represented in
-    these languages and presents them as OpenSpiel games. This could lead to the
-    potential of evaluating learning agents on hundreds to thousands of games.
+    [Ludii General Game System](http://www.ludii.games/index.html) or
+    [GAMUT](http://gamut.stanford.edu/) (a suite of normal-form game
+    generators). A very nice addition to OpenSpiel would be a game that
+    interprets games represented in these languages and presents them as
+    OpenSpiel games. This could lead to the potential of evaluating learning
+    agents on hundreds to thousands of games.
 
 -   **Go API**. We currently have a prototype [Go](https://golang.org/) API
     similar to the Python API. It is exposed using cgo via a C API much like the
@@ -157,8 +159,8 @@ release!). Contributions are certainly not limited to these suggestions!
 -   **Grid Worlds**. There are currently four grid world games in OpenSpiel:
     Markov soccer, the coin game, cooperative box-pushing, and laser tag. There
     could be more, especially ones that have been commonly used in multiagent
-    RL. Also, the current grid worlds can be improved: all use fixed grids and
-    are fully-observable.
+    RL. Also, the current grid worlds can be improved (they all are
+    fully-observable).
 
 -   **Heuristic Payoff Tables and Empirical Game-Theoretic Analysis**. Methods
     found in