Update Gaia API documents for #93c498debcce6249eec5dbaff313a6f0120c0249
    Bug 947918: Support seeking to end of BlobView buffer

Reading or advancing through all bytes in a BlobView buffer sets
the index to the length of the buffer. This patch changes 'seek'
to work the same way, so it's possible to seek to the buffer's
end.

Signed-off-by: Thomas Zimmermann <tdz@users.sourceforge.net>