request: additional ISA's

[mcandre]

Hi,

I love Go's inherent portability across architectures. I see that the techknowlogick/xgo images currently support linux/amd64 and linux/arm64. Can we please expand these to include more of the architectures that Go supports? So that CGo users can build our applications for more platforms.

For comparison, Docker Hub's official golang image supports more of these other architectures:

https://hub.docker.com/_/golang