Code to handle the internal states of modulecmd have been reworked on
Modules v4.6. As a consequence several siteconfig.tcl extension scripts
described on documentation recipes have to be adapted.
Closes#396
Add a cookbook section in the documentation and port there the 3
pre-existing recipes: inhibit-report-info, top-priority-values and
unload-firstly-loaded.
Move the examples files of these recipes from contrib/cookbook to
doc/example directory.