Add facilities open data repositories to open data tab

• move current resources into a "disciplinary repositories" or similar
• add a section for PaN facilities repositories, include the sort of information we have in panosc.eu

mentioned in commit 9146953a

1st version done.
Remaining:

• check errors on OAI-PMH endpoints
• find missing PaN search API endpoints

closed

Closing anyway, the remaining tasks fall into 'contributing'.