2-way cherry-pick from oc-preview-docs-release: docs: Updated ShortcutManager...

2-way cherry-pick from oc-preview-docs-release: docs: Updated ShortcutManager Javadoc for Android O Developer Preview.

Test: make ds-docs -j12

Bug: 34685739
Change-Id: Ie70977f9b7b5b08de8bdd583a1e21b8a00eb5970
Original-Change-Id: I3cfa360ebd025a7eb198d7fe54f96059f42cd7f5
Original-Change-Id: I45ef30010f696604c06ce2cd7e2eca1db012e68b