Offering a bonus in app description?


I want to include a short message in my apps description, saying that if people will share the application on social media networks, I will send them a free eBook (related to my app) as a sign of my appreciation - all they need to do is send me an e-mail and I’ll reply with the eBook included.

I’ll also include this message in my app, but I’m not sure, if it’s OK to say it in the description. All I was able to found in their TOS is this:

Can you guys please help me with clearing up this issue? Thanks.