Update DownloadManager.addCompletedDownload javadoc.

Starting from Q, downloads added using
DownloadManager.addCompletedDownload are by default going to
be added to MediaProvider regardless of isMediaScannerScannable
argument specified by clients. Update the javadoc to reflect this.

Bug: 120876251
Test: n/a
Change-Id: Ie091703d801bb9cecc9574a122e13a242f4cca95
1 file changed