AU Base Medication Dispense QA fixes

[dbojicic-agency]

Fixes #534.

• AU Base Medication Dispense:

  • replaced identifier slice with Identifier data type profile
  • removed unnecessary shorts and definitions, and added where required (due to IG building tooling)
  • updated metadata

• intro content

  • added standard HL7 AU Base paragraphs
  • removed Medication Reference/Coding sub-heading and moved the content into Usage Notes with added links to value sets & source organisation pages
  • linked to Identifier profile data type
  • reformatted extensions list
  • moved text from the extensions list into new sub-heading Usage Notes
  • added Examples sub-heading and standard no examples available text