Fix vectorvalue docs #12940

Job	Run time
Build Firestore	9m 5s
Test Firestore Compatible	5m 8s
Test Firestore Compatible on Firefox	7m 27s
Test Firestore Compatible on Webkit	4m 31s
Test Firestore (test:browser)	8m 9s
Test Firestore on Firefox (test:browser)	11m 26s
Test Firestore (test:travis)	4m 0s
Test Firestore on Firefox (test:travis)	3m 58s
Test Nightly Firestore with Chrome	0s
Test Firestore (test:lite:browser)	1m 44s
Test Firestore on Firefox (test:lite:browser)	1m 46s
Test Firestore (test:browser:prod:nameddb)	10m 1s
Test Firestore on Firefox (test:browser:prod:nameddb)	9m 54s
Test Firestore (test:lite:browser:nameddb)	1m 26s
Test Firestore on Firefox (test:lite:browser:nameddb)	1m 46s
Test Firestore on Webkit (test:browser)	11m 38s
Test Firestore on Webkit (test:lite:browser)	1m 57s
Test Firestore on Webkit (test:browser:prod:nameddb)	11m 54s
Test Firestore on Webkit (test:lite:browser:nameddb)	2m 33s
Check all required tests results	1s
	1h 48m 24s

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