[docbook] Configure Emacs to autocomplete the tags

[Markos]

Hi,

I just installed Debian Jessie and installed the packages to use DocBook 
with Emacs:

||bash# | apt-get install /|docbook-xsl xsltproc|/|

||bash# | apt-get install /|emacs |/|


What I need to do to for Emacs to autocomplete thetags.

This feature worked in Squeeze.

Any tip?

Thanks,
Markos