Fix semicolon error

Author: martgnz

snippets/margin.cson

@@ -2,7 +2,7 @@
     "Append a SVG with the margin convention":
         prefix: "margin"
         body: """
-        var margin = {top: ${1:20}, right: ${2:10}, bottom: ${3:20}, left: ${4:10}};
+        var margin = {top: ${1:20}, right: ${2:10}, bottom: ${3:20}, left: ${4:10}},
             width = ${5:960} - margin.left - margin.right,
             height = ${6:500} - margin.top - margin.bottom;