Why is the Didache not included in the Bible?

Why are these teachings not included in the books of the New Testament of the Bible? They are quoted in the Catechism, and would seem to be among the most trusted texts out there to supplement and support the teachings of Jesus.
What’s the official reason for the Catholic Church not including them?

The Didache was not included in the Bible because it never gained wide acceptance as inspired Scripture by the full Christian community. The Didache is analogous to what we today would call a Catechism.

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