add chat action constants

README.md

@@ -368,7 +368,10 @@ See the [*ImageCommand.php*][ImageCommand.php] for a full example.
 #### Send Chat Action
 
 ```php
-Request::sendChatAction(['chat_id' => $chat_id, 'action' => 'typing']);
+Request::sendChatAction([
+        'chat_id' => $chat_id, 
+        'action' => Longman\TelegramBot\Telegram::ACTION_TYPING
+]);
 ```
 
 #### getUserProfilePhoto

src/Telegram.php

@@ -25,6 +25,57 @@ use RegexIterator;
 
 class Telegram
 {
+
+    /**
+     * Typing chat action
+     */
+    const ACTION_TYPING = 'typing';
+
+    /**
+     * Upload Photo chat action
+     */
+    const ACTION_UPLOAD_PHOTO = 'upload_photo';
+
+    /**
+     * Record Video chat action
+     */
+    const ACTION_RECORD_VIDEO = 'record_video';
+
+    /**
+     * Upload Video chat action
+     */
+    const ACTION_UPLOAD_VIDEO = 'upload_video';
+
+    /**
+     * Record Audio chat action
+     */
+    const ACTION_RECORD_AUDIO = 'record_audio';
+
+    /**
+     * Upload Audio chat action
+     */
+    const ACTION_UPLOAD_AUDIO = 'upload_audio';
+
+    /**
+     * Upload Document chat action
+     */
+    const ACTION_UPLOAD_DOCUMENT = 'upload_document';
+
+    /**
+     * Find Location chat action
+     */
+    const ACTION_FIND_LOCATION = 'find_location';
+
+    /**
+     * Record Video Note chat action
+     */
+    const ACTION_RECORD_VIDEO_NOTE = 'record_video_note';
+
+    /**
+     * Upload Video note chat action
+     */
+    const ACTION_UPLOAD_VIDEO_NOTE = 'record_video_note';
+
     /**
      * Version
      *