Update Tanzu Tile variable descriptions (#3724) #9

Job	Run time
setup-environment	2m 43s
tidy	2m 55s
gofmt	6m 8s
coverage	9m 14s
cross-compile (binaries-darwin_amd64)	6m 42s
generate-metrics	6m 7s
cross-compile (binaries-darwin_arm64)	6m 49s
lint	30m 5s
test	17m 54s
cross-compile (binaries-linux_amd64)	8m 49s
cross-compile (binaries-linux_arm64)	6m 51s
cross-compile (binaries-windows_amd64)	8m 15s
cross-compile (binaries-linux_ppc64le)	8m 35s
	2h 1m 7s

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