What can i do to get Request_Contact button from Telegram API

So basically i want to get the phone number of the user ,since i cant just extract it from the user from the get_metadata(), i read from : Telegram Bot API and Introducing Bot API 2.0 that i can use the keyboard button from the telegram API but how can i use it, can somebody help me i have also read the documentation Telegram but just cant find on how to implement it .

Thanks for sharing that. You know I am finding that type of information and I get here.