Add new page on including metadata in NeuroML model descriptions

[sanjayankur31]

use of NeuroLexID, and annotations to include general RDF metadata

• https://github.com/OpenSourceBrain/OSB_API/blob/master/python/examples/granulecell.xml
• http://identifiers.org/
• https://scicrunch.org/scicrunch/interlex/dashboard

[sanjayankur31]

Current combine spec: https://github.com/combine-org/combine-specifications/blob/main/specifications/omex-metadata.md

library: https://pypi.org/project/pyomexmeta/

[sanjayankur31]

Done: https://docs.neuroml.org/Userdocs/Provenance.html