Fixed color tutorial content

Author: rishab

content/tutorials/text/color/index.mdx

@@ -130,7 +130,7 @@ rect(0,0,200,40);
 fill(255,0,0,191);
 rect(0,50,200,40);
 
-// 55% opacity.
+// 50% opacity.
 fill(255,0,0,127);
 rect(0,100,200,40);