WhatsApp now introduced Document File transfer in their Android application so that doc and pdf type files can be sent through the application. The new feature is not available in the Google Play Store version. Currently it can be downloaded from the WhatsApp website. After the testing completed, it will be available in Google Play Store also.
WhatsApp is constantly updating the application with new features every time. Recently they introduced backup to Google Drive, earlier, the Voice Call etc. Now they introduced the Document Transfer feature. PDF and DOC files can be now transfer using this feature. With the addition of this feature, now any types of file such as jpeg, png, gif, pdf, doc, mp4, 3gp etc can be sent through whatsApp.
The new feature will be available in the version 2.12.489. If your application is not updated, you can manually update it by downloading from the WhatsApp website.