Fix ontodoc for bigmap

[jesper-friis]

Description:

Fixed the following two issues with html generation in ontodoc:

• http://emmo.info in IRIs became http://emmo:info in the generated html
• html anchors for IRIs was preflabels. They are now changed to the 'name' part of the IRI (i.e. everything that follows the hash)

The solution with anchors relies on a markdown extension that is specific to Pandoc. Maybe not ideal, but much better than implementing yet a postprocessing step that I stated with...

Type of change:

• Bug fix.
• New feature.
• Documentation update.

Checklist:

This checklist can be used as a help for the reviewer.

• Is the code easy to read and understand?
• Are comments for humans to read, not computers to disregard?
• Does a new feature has an accompanying new test (in the CI or unit testing schemes)?
• Has the documentation been updated as necessary?
• Does this close the issue?
• Is the change limited to the issue?
• Are errors handled for all outcomes?
• Does the new feature provide new restrictions on dependencies, and if so is this documented?

Comments: