Add a doc about deploy failures #7940

Job	Run time
markdownlint	24s
check-git-conflicts	9s
verify-internal-links	31s
check-file-encoding	9s
check-manual-line-breaks	10s
check-control-characters	9s
check-unclosed-tags	9s
verify-internal-link-anchors	15s
	1m 56s

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