genomics: use smaller buffers

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
documentation: update guidelines

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
genomics: respect the maximum number of requests

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
genomics: fix regulation in vertex extraction

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>