add netlify.toml configuration
add netlify.toml configuration

This is part of https://github.com/kubernetes/org/issues/3177, which
itself is a part of https://github.com/kubernetes/test-infra/issues/24821.

dims/test-infra,michelle192837/test-infra,kubernetes/test-infra,kubernetes/test-infra,cblecker/test-infra,jessfraz/test-infra,jessfraz/test-infra,cjwagner/test-infra,dims/test-infra,BenTheElder/test-infra,jessfraz/test-infra,jessfraz/test-infra,BenTheElder/test-infra,jessfraz/test-infra,michelle192837/test-infra,fejta/test-infra,monopole/test-infra,monopole/test-infra,michelle192837/test-infra,cblecker/test-infra,monopole/test-infra,cjwagner/test-infra,cblecker/test-infra,fejta/test-infra,fejta/test-infra,cblecker/test-infra,michelle192837/test-infra,monopole/test-infra,dims/test-infra,dims/test-infra,dims/test-infra,BenTheElder/test-infra,cjwagner/test-infra,kubernetes/test-infra,cjwagner/test-infra,BenTheElder/test-infra,cblecker/test-infra,BenTheElder/test-infra,cblecker/test-infra,michelle192837/test-infra,kubernetes/test-infra,dims/test-infra,monopole/test-infra,BenTheElder/test-infra,cjwagner/test-infra,kubernetes/test-infra,michelle192837/test-infra,fejta/test-infra,jessfraz/test-infra,cjwagner/test-infra,fejta/test-infra,monopole/test-infra,fejta/test-infra,kubernetes/test-infra