Could the USE_REL_REV customization variable of texi2any be removed? It is does not seem very useful to disable use of the 'rel' attribute and I propose that these attributes be output unconditionally.
Here's what the manual says: ...if the ‘USE_REL_REV’ customization variable is set, the default, the ‘rel’ attribute is used in navigation to define the relationship between the current page and the linked resource. For example, the ‘contents’ ‘rel’ attribute is set for a link to the table of contents, the ‘next’ ‘rel’ attribute is set for a link to the next node or section. It is set to '0' for TEXI2HTML=1. The name is confusing as well, as it does not touch the 'rev' attribute of HTML elements, only 'rel'.
