docs: update "Life of a Prow Job"
docs: update "Life of a Prow Job"

This cleans up this doc and brings all links up to date to
5df7636b83cab54e248e550a31dbf1e4731197a6. We prefer to link to the
generated Go docs where applicable, to encourage codebase exploration
for the reader.

We also use link references to make the code easier to edit in the future.

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