Suggestion: explain HTTP "422 Unprocessable Entity" error in API docs

Using the API to send datapoints to Beeminder, I got a 422 error and was puzzled for a minute. Like, what “unprocessable” stuff am I sending? It’s just the response to the same datapoint being posted twice.

The API docs don’t mention this, even in the section at the bottom with all the other HTTP error codes. I think this would be a nice thing to note, that even though the endpoint is “idempotent”, as mentioned, it will send the 422 error for duplicate requests when adding a datapoint.

That’s all, thanks!