Update mapping documentation for canonical URLs

[paynejd]

First round of edits completed here: https://docs.openconceptlab.org/en/latest/oclapi/apireference/mappings.html

Additional changes needed:

• Add to the Overview:
  • [ ] New Auto-ID behavior (see here)
  • [ ] Sort weight
  • [ ] Support canonical URLs
  • [ ] How to interact with OCL mappings via the OCL FHIR Core (and vice versa)
• [x] Confirm whether repo version can be specified separately or inline for each of the 3 approaches
• [ ] Update all examples to use canonical URLs
• [ ] Update response examples with all of the new fields
• [ ] Add OpenMRS specific examples

Here's an example API resource: https://api.qa.openconceptlab.org/orgs/CIEL/sources/CIEL/concepts/164505/?includeMappings=true

[paynejd]

@jamlung-ri to add documentation on:

• auto-id
• sort weight

Confirmed that documentation for handling of repo versions matches the current implementation, but ideally we would use $resolveReference to handle mapping repo resolution as well, which would give us piped versions for canonical URLs for free -- created a ticket for this here: #1714

[jamlung-ri]

@jamlung-ri to add documentation on:

* auto-id

* sort weight

Brief documentation and examples added on the Create Source page and the Mappings page.