With the latest version of Whatsapp, It’s now possible for its users to send and receive document files like .pdf, etc.
This new feature has only welcomed the sending and receiving of only PDF files and nothing more.
Before now, Whatsapp is known mostly for only chatting and sending media files like music, videos, pictures etc and nothing like document file.
Note: A Whatsapp user won’t be able to send not until the receiver has also updated his/her Whatsapp application.
To be able to use this feature, Kindly head to Google play store and update your Whatsapp application from version 2.12.453 to version 2.12.489.
After updating, Tap the attachment icon in the receivers chat and pick the fresh blue Document icon. A new page will appear and choose the desired PDF to send.
Kindly share with your friends.

Source: http://www.gidimasters.com/2016/03/how-to-send-document-files-like-pdf-on.html