fix jsdoc description

Author: brettz9

lib/rules/prefer-for-of.js

@@ -211,13 +211,13 @@ function isAssignee(startNode) {
 }
 
 /**
- * Checks whether the all references of the index variable are used to get
+ * Checks whether all references of the index variable are used to get
  * array elements.
  *
  * @param {RuleContext} context - The rule context object.
  * @param {ASTNode} node - The `for` loop node which is a simple array
  * traversing.
- * @returns {boolean} `true` if the the all references of the index variable are
+ * @returns {boolean} `true` if all references of the index variable are
  * used to get array elements.
  */
 function isIndexVarOnlyUsedToGetArrayElements(context, node) {