Support multi-file $KUBECONFIG

[prydie]

Removes caching in favour of multiple $KUBECONFIG support.

Fixes: #8

[superbrothers]

I'm sorry for the late reply 🙇.

Removing caching occurs to make terminal's response slow. I'd like to seek another solution.

[fhemberger]

@prydie @superbrothers Multiple configs in $KUBECONFIG are separated by colons. How about just splitting the string?

kubeconfigs=("${(@s/:/)kubeconfig}")
for config in $kubeconfigs; do
	echo $config
	# ...
done