The extension generates documents about python module API but it is not
actually used.
Also drop note about old pip's behavior. Recent pip can resolve
dependencies automatically.
Change-Id: If5ea5ec2a89b65732ec14c5ceabededf3d60183e
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>
73cb920ad4