Improve documentation of ScheduleLambda #85540

Job	Run time
Build framework (macos-release, -sdk macosx -configuration Release)	10m 52s
Build framework (macos-release, -sdk macosx -configuration Release)	10m 52s
Build framework (ios-release, -sdk iphoneos -configuration Release)	8m 7s
Build framework (ios-release, -sdk iphoneos -configuration Release)	8m 7s
Build framework (tvos-debug, -sdk appletvos -configuration Debug)	6m 47s
Build framework (tvos-debug, -sdk appletvos -configuration Debug)	6m 47s
Build framework (watchos-debug, -sdk watchos -configuration Debug)	20m 24s
Build framework (watchos-debug, -sdk watchos -configuration Debug)	20m 24s
Run framework tests (asan, -enableAddressSanitizer YES -enableUndefinedBehaviorSanitizer YES)	26m 43s
Run framework tests (asan, -enableAddressSanitizer YES -enableUndefinedBehaviorSanitizer YES)	26m 43s
Run framework tests (tsan, -enableThreadSanitizer YES)	36m 12s
Run framework tests (tsan, -enableThreadSanitizer YES)	42m 19s
Run framework tests (leaks, ENABLE_LEAK_DETECTION=1)	25m 37s
Run framework tests (leaks, ENABLE_LEAK_DETECTION=1)	25m 37s
	4h 35m 31s

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