Fix invalid links when generating pdf of continuum-docs

When generating a pdf of the continuum-docs module, we get a bunch of warnings:

INFO] [pdf:pdf

]
[WARNING] [APT Parser] Modified invalid link: 'administrator_guides/index.html' to '#administrator_guidesindex.html'
[WARNING] [APT Parser] Modified invalid link: 'developer_guides/building.html' to '#developer_guidesbuilding.html'
[WARNING] [APT Parser] Modified invalid link: 'installation/geronimo.html' to '#installationgeronimo.html'
...

We need to fix the links in the apt pages so they are correct in the generated pdf.