release-notes: document ceph-ansible-rgw-multisite image for OSISM 10

[berendt]

Document the availability of the dedicated ceph-ansible-rgw-multisite container image which provides support for Ceph RGW Multisite deployments for Quincy, Reef, and Squid releases.

AI-assisted: Claude Code

[github-actions]

✅MegaLinter analysis: Success

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	3		0	0	0.04s
✅ JSON	jsonlint	4		0	0	0.18s
✅ JSON	prettier	4		0	0	0.58s
✅ JSON	v8r	4		0	0	7.15s
✅ MARKDOWN	markdownlint	159		0	0	2.14s
✅ MARKDOWN	markdown-table-formatter	159		0	0	0.3s
✅ REPOSITORY	checkov	yes		no	no	18.65s
✅ REPOSITORY	git_diff	yes		no	no	0.06s
✅ REPOSITORY	secretlint	yes		no	no	1.82s
✅ REPOSITORY	trufflehog	yes		no	no	3.95s
✅ SPELL	cspell	189		0	0	5.91s
✅ SPELL	lychee	176		0	0	8.87s
✅ YAML	prettier	5		0	0	0.32s
✅ YAML	v8r	5		0	0	7.22s
✅ YAML	yamllint	5		0	0	0.32s

See detailed reports in MegaLinter artifacts

Your project could benefit from a custom flavor, which would allow you to run only the linters you need, and thus improve runtime performances. (Skip this info by defining FLAVOR_SUGGESTIONS: false)

• Documentation: Custom Flavors
• Command: npx mega-linter-runner@9.3.0 --custom-flavor-setup --custom-flavor-linters ACTION_ACTIONLINT,JSON_JSONLINT,JSON_V8R,JSON_PRETTIER,MARKDOWN_MARKDOWNLINT,MARKDOWN_MARKDOWN_TABLE_FORMATTER,REPOSITORY_CHECKOV,REPOSITORY_GIT_DIFF,REPOSITORY_SECRETLINT,REPOSITORY_TRUFFLEHOG,SPELL_CSPELL,SPELL_LYCHEE,YAML_PRETTIER,YAML_YAMLLINT,YAML_V8R