Add descriptions to transformation/transformers/es6/constants

src/babel/transformation/transformers/es6/constants.js

@@ -1,13 +1,29 @@
 import * as messages from "../../../messages";
 
 /**
- * [Please add a description.]
+ * Turn constants into variables.
+ * Ensure there are no constant violations in any scope.
+ *
+ * @example
+ *
+ * **In**
+ *
+ * ```javascript
+ * const MULTIPLIER = 5;
+ * ```
+ *
+ * **Out**
+ *
+ * ```javascript
+ * var MULTIPLIER = 5;
+ * ```
  */
 
 export var visitor = {
 
   /**
-   * [Please add a description.]
+   * Look for any constants (or modules) in scope.
+   * If they have any `constantViolations` throw an error.
    */
 
   Scope(node, parent, scope) {
@@ -24,7 +40,8 @@ export var visitor = {
   },
 
   /**
-   * [Please add a description.]
+   * Look for constants.
+   * Turn them into `let` variables.
    */
 
   VariableDeclaration(node) {