Punctuation; formatting

Author: meglio

webgl/lessons/webgl-attributes.md

@@ -146,7 +146,7 @@ attributes: [
    ..
 ```
 You can set each attribute's value with the various `gl.vertexAttribXXX`
-functions. The value is used when `enable` is false. When enable is true data for
+functions. The value is used when `enable` is false. When `enable` is true, data for
 the attribute is pulled from the assigned buffer.
 
 <a id="vaos"></a>