Completion: Updates to www.debian.org/devel/constitution (and former versions), and note to translators

Hi again:

> Translators: I think that the best way to sync translations is to copy your
> "/devel/constitution.wml" file to "constitution.1.7.wml", and then edit the
> constitution.wml file to reflect the actual changes to the constitution and that
> we're now in version 1.8.
> 
> The files for the historical versions of the constitution (1.0 to 1.7) will also
> need small updates (to update links in all the historic constitutions and use
> consistent formatting for the links between constitutions)

For completion, it's also needed to update the commit hash in the
translation-check header of constitution.1.7.wml to
5a315ddb15a28dd0269d23be676be33d0f75f371

Kind regards,