The documentation also doesn't make it clear because it links TinyDNS format, but says you're using a simplified version without mentioning any real details.
Are there any plans to support / document these other record types?
The missing record-types are highlighted as a concern, and it should be possible for me to add them quickly.
I've launched now mostly to see if there is a demand for this middle-ware - rather than having people jump-ship immediately to Amazon. (Plus I find the idea of Git being used neat.)
So, in conclusion yes missing SRV, missing TXT, and they will come.
I've just switched to using git for the zones I administer myself. Haven't been brave enough to look into using hooks yet though!