doc-rst: include index only in subproject AND html

The index should only be included if the build of the sub-folder is done
with the html-builder (HTML output).

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

0 files changed, 0 insertions, 0 deletions