feat: add NCBO BioPortal link

[jsstevenson]

address #80 ? I didn't read the rest of the conversation, not sure if there's more work to be done there outside of this.

• Add button to link to corresponding NCBO BioPortal page
• Update other browser links to proper external links
• Special cases are all hard coded rather than figuring out a regex. It's implemented as a custom liquid plugin, should be fairly easy to update if necessary.

[matentzn]

Assuming it works this looks greeeat!!! THANKS!

[matentzn]

Boom.

[matentzn]

@jsstevenson somehow the BioPortal links are lowercased on the site?
https://obofoundry.org/ontology/mondo.html

[jsstevenson]

@matentzn ...bizarre. This was working locally. Give me a minute

[jsstevenson]

Oh, right, the way we're deploying the Jekyll site won't support custom liquid plugins. I'll need to do a quick fix

[nataled]

PRO already had a working BioPortal link. There are now two (the second, new link, is non-working).

[jsstevenson]

Alright, sorry about that. Fix for both is in #2655. This was working locally (although I missed the extra browser links for PRO et al) but GitHub's native jekyll deployment places some limits on the kinds of plugins you can add yourself.