Well, if you have a substantial amounts of bitcoins which can effect your heirs life in a positive way, I will recommend you to add it to your will. Don't mention the private key to your will, instead store the details of your bitcoin wallet in a secure location in your laptop or PC or in a piece of paper and mention that location details to your will, so that your heirs can find it after your death.
Else, have some faith on your wife and tell her everything about your bitcoins. Let her know how to access it and ask her to distribute it among your children after your death. But if you are holding a very small amount, then it's not worth having the bitcoin details included in your will.
I think no need to make a will of testament just to remind them about your Bitcoin or Cryptocurrency wealth. Your wife or your closest sibling will be the best person to entrust all your digital wealth because nobody knows what will happen. If we die they can still use our digital wealth.
That's the best thing, introduce Bitcoin and Crypto-Currency and Blockchain technology to your family in order to remind them that if one of the family member is gone then they can still access your assets.
Even i think the same! What's the need of mentioning it in your will or Testament. One can simply inform a trustworthy peer or relative about the earned wealth. Actually this is a prudent and a rational decision. Because you never know when life takes a toll on you. So it's better if you have saved through this medium do keep some reliable person informed about this. What good is your wealth if it couldn't serve your loved ones!!
It's as simple as that. That concerned person may act as your heir or a nominee at the time of your death and would be able to utilize your funds instead of them getting wasted.