docs: name the gate's release record for the namespace as well as the Application

[ExtraToast]

Summary

The Release Gate's record is named <namespace>.<application>-release-record, where chapter 55 said <application>-release-record.

• Why. The commit review of feat: start and undo migrations from the gate's inputs, record what serves, and report held releases delivery#23 found that a record named by Application id alone is first-come: inputs put under an Application's id in another namespace, tended before the real Application exists, would claim its record, and the real one could then never write it.
• Why the dot. A namespace is a DNS label and holds no dot, so the first dot says where it ends, whatever the Application id holds.

To know

• Wording only; nothing renders the record, and no oracle or implementation changes.
• The gate side is feat: start and undo migrations from the gate's inputs, record what serves, and report held releases delivery#23.

Part of #195.

[github-actions]

Shape

bucket	files	additions	deletions
specification	1	+7	-4

Coverage

Baseline: main @ f417250.

metric	this branch	main	diff
statements	99.61%	99.61%	0.00
branches	98.35%	98.33%	+0.02
functions	100.00%	100.00%	0.00
lines	99.57%	99.57%	0.00

This pull request changed no covered line.