I'll begin by clearing up any possible misunderstandings based upon different senses of some language. There are a couple of key terms here. Facts are what's happened and/or is happening. The term "moral" is being used to pick out any and all situations involving acceptable/unacceptable behaviour. So, moral facts are a kind of situation/fact, not a value assessment thereof based upon belief about what counts as acceptable/unacceptable behavior.

Situations involving discussions about acceptable/unacceptable behavior are moral facts.

When we discuss a making a promise, we are discussing the act of giving one's word to make the world match their words. To make a promise is to voluntarily obligate oneself to do what they promise to do.

Nothing too objectionable there.

Now, let us introduce the idea of true statements about the moral facts...

When one promises to plant a rose garden on Sunday, then on Monday there ought be a rose garden. The second statement is true, and it contains an ought.