Fix lifecycle doc to refer to json instead of xml
Fix lifecycle doc to refer to json instead of xml

ttiurani/gsutil,mattdr/gsutil,GoogleCloudPlatform/gsutil,BrandonY/gsutil,dtjackson/gsutil,dimfeld/gsutil,GoogleCloudPlatform/gsutil,fishjord/gsutil,craigcitro/gsutil,chriskuehl/gsutil-debian