The documentation is generated in HTML only.
The PDF format is abandoned since DPDK 20.11
while dropping support of the make-based build.
This decision has been mentioned by the Technical Board:
https://mails.dpdk.org/archives/dev/2021-January/195549.html
Fixes: 3cc6ecfdfe85 ("build: remove makefiles")
Cc: stable@dpdk.org
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>