tools: fix building doc in build_release.sh
tools: fix building doc in build_release.sh

Fixes: 3b2071e970995a9a22d46457e60a762161b46231

thom311/libnl,dsahern/libnl,greearb/libnl-ct,thom311/libnl,greearb/libnl-ct,dsahern/libnl,dsahern/libnl,tklauser/libnl,tklauser/libnl,thom311/libnl,dsahern/libnl,greearb/libnl-ct,tklauser/libnl,tklauser/libnl