Update webgl-state-diagram.html (#449)

Author: mollerhoj

webgl/lessons/resources/webgl-state-diagram.html

@@ -271,7 +271,7 @@
 
 ## Notes:
 
-* A programs only indirectly
+* Programs only indirectly
   reference textures via texture units by index. Similarly 
   programs only indirectly reference buffers via vertex
   array attribute index. The arrows showing