Add root annotation to BTO

[cthoyt]

Related to OBOFoundry/OBOFoundry.github.io#2149

What This PR Does

Applies the annotation property has ontology root term (IAO:0000700) at the the ontology level to list the following terms from this ontology as "root terms":

1. BTO:000000

Why this is helpful

• the Ontology Lookup Service uses this to help better display ontologies
• if any of the terms mentioned above are ever aligned with an upper ontology like BFO, it still will be the thing shown on OLS as the "root"
• this will be generally useful for things like alignment with COB since it makes it easier to figure out what are the upper level terms in this ontology are

CC @chdudek @BRENDA-Enzymes

[chdudek]

Thank you for your contribution @cthoyt!

The BRENDA team currently working on a fix for #10 and other outstanding problems outdated references etc.). I will look into the open pull requests afterwards before the next BTO update.

[cthoyt]

@chdudek is there anything I can do in the mean time?

[chdudek]

As the fix for #10 is a larger task and will take longer as expected, I've merged your change to the repository. Sorry for the delay.