docs(localStorage): update docs to use correct types

References ionic-team/ionic-site#546

ionic/platform/storage/local-storage.ts

@@ -22,7 +22,7 @@ import {StorageEngine} from './storage';
  * export class MyClass{
  *  constructor(){
  *    this.local = new Storage(LocalStorage);
- *    this.local.set('didTutorial', true);
+ *    this.local.set('didTutorial', 'true');
  *  }
  *}
  *```
@@ -36,7 +36,7 @@ export class LocalStorage extends StorageEngine {
 
   /**
    * Get the value of a key in LocalStorage
-   * @param {String} key the key you want to lookup in LocalStorage
+   * @param {string} key the key you want to lookup in LocalStorage
    */
   get(key: string): Promise<string> {
     return new Promise((resolve, reject) => {
@@ -51,8 +51,8 @@ export class LocalStorage extends StorageEngine {
 
   /**
    * Set a key value pair and save it to LocalStorage
-   * @param {String} key the key you want to save to LocalStorage
-   * @param {Any} value the value of the key you're saving
+   * @param {string} key the key you want to save to LocalStorage
+   * @param {string} value the value of the key you're saving
    */
   set(key: string, value: string): Promise<any> {
     return new Promise((resolve, reject) => {
@@ -67,7 +67,7 @@ export class LocalStorage extends StorageEngine {
 
   /**
    * Remove a key from LocalStorage
-   * @param {String} key the key you want to remove from LocalStorage
+   * @param {string} key the key you want to remove from LocalStorage
    */
   remove(key: string): Promise<any> {
     return new Promise((resolve, reject) => {