Added docs for custom Firebase Storage CDN #8932

Job	Run time
Automated Code Review	7m 49s
Launch Allure TestOps	32s
Build Test App and Frameworks	4m 37s
Build LLC + UI (Xcode 14)	33s
Build Demo App + Example Apps	1m 13s
Test LLC (Debug)	2m 1s
Test Integration	59s
Test E2E UI (Debug) (0)	2m 4s
Test E2E UI (Debug) (1)	2m 22s
Test E2E UI (Debug) (2)	2m 53s
Test UI (Debug)	1m 35s
	26m 38s

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