Fix a typo in README.md (#605)

diff --git a/doc/README.md b/doc/README.md
index c9993a9..0eb7b76 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -239,7 +239,7 @@
   * the edge between `read` and `(*rngSource).Int63`:
     * Since it is a solid edge, there are no nodes between those two (i.e. it
       was a direct call).
-    * Since it is thin and grey, fewer resrouces were used in call stacks
+    * Since it is thin and grey, fewer resources were used in call stacks
       between those two nodes.
   
 ## Annotated code