Implement browsable UI for schemas, standards, ontologies

[ronaldtse]

The goal is to make schema/resources browsable. This applies to these sites:

• https://schemas.isotc211.org
• https://def.isotc211.org
• https://standards.isotc211.org (there's only placeholder content, but still needs to be browsable)

This shall come in a form of a plugin so it applies across the board.

We should have a _config.yml directive that lists out what "directories" should be browsable.

• If the directory (and its sub-directories) do not have index.html, supply it.
• The index.html should be a listing of the directory it belongs to, aka ls -l

Originally posted by @ronaldtse in https://github.com/ISO-TC211/www.isotc211.org/issues/27#issuecomment-521042933

[strogonoff]

@ronaldtse A question about the orphans directory within the ontology repository dataset.

It seems like it contains files (appropriate to its name) not belonging to any particular ontology.

• Is that resource temporary, or it’s expected to be existing normally?

• If it’s inevitable, perhaps data could be rearranged so that “orphans” is not located among ontologies? It would allow for a more elegant solution if directory contents were homogenous & we could treat each subdirectory as an ontology, with ontology ID as subdirectory name.

[strogonoff]

(b9eeba6)

[ronaldtse]

@strogonoff posted to ISO-TC211/ontologies#1 now, will revert.

[strogonoff]

From what I understand after reading comments over there, we may be able to restructure directories to move orphans outside ontology list. (Edit: I’m wrong, we’ll have to live with it for now.)