fix(index): comments

Author: mrmlnc

lib/index.js

@@ -228,7 +228,7 @@ function walk (opts, nodes) {
 
     // switch tag
     if (node.tag === switches[0]) {
-      // throw an error if it's missing the "condition" attribute
+      // throw an error if it's missing the "expression" attribute
       if (!(node.attrs && node.attrs.expression)) {
         throw new Error(`the "${switches[0]}" tag must have a "expression" attribute`)
       }