playground/README: Simplify description, remove out of date info.

dmitshur · dmitshur · commit 6174d2eee081 · 2016-02-21T14:34:40.000-08:00
diff --git a/playground/README.md b/playground/README.md
@@ -1,8 +1,6 @@
 # GopherJS Playground
 
-The playground is a place where users can explore GopherJS without needing to install anything, or to share code with others. Our motivation should be that a potential user could easily be turned of by a bad experience here.
-
-A secondary motivation is making the playground usable for other projects, such as in the GopherJS book, a GopherJS codewalk, or custom interactive environments using other packages.
+The playground is a place where users can explore GopherJS without needing to install anything, or to share code with others.
 
 ## Development
 
