Add a wrapper tag for odoc index pages.
Add a wrapper tag for odoc index pages.

Signed-off-by: Rizo Isrof <29c73dc722c8e92a39938cffb847c9c8f107ca0b@odis.io>

janestreet/jbuilder,dra27/jbuilder,janestreet/jbuilder,dra27/jbuilder,dra27/jbuilder,janestreet/jbuilder,janestreet/jbuilder,dra27/jbuilder,janestreet/jbuilder,dra27/jbuilder,dra27/jbuilder,janestreet/jbuilder