Pluralise codelists names consistently
Update text explaining OrganisationRegistrationAgency is NonEmbedded
Add missing codes from 1.03 website

This is an alternative approach to
https://github.com/IATI/IATI-Codelists-NonEmbedded/commit/f132749776621acb7051254d35ab567a28a3d00f

Instead of reverting all codelists to their state on the 1.03 website,
additions have been preserved, but deletions (since they have not been
agreed) have been reverted.
[#12] Update LocationType source url
[#11] Link to Organisation Identifiers guidance
Add missing dac external urls