Update README to add examples of the type of content

We have a non-intuitive split between this package and the -demo package. This tries to better clarify things

Author: ibacher

README.md

@@ -1,11 +1,16 @@
 # OpenMRS Reference Application Content
 
-This is a template repo to be used to set up and share Content Packages.
-
 This content package contains the baseline metadata necessary to run a verison of O3. Please note that while
 the metadata here is all that's _required_, this does not provide the metadata necessary for every feature to
 work. That is because the metadata needed for various things, like the formulary or procedure catalog is
 expected to be customized for most sites.
 
 Additional metadata used in the O3 demo environments is contained in the Reference Application Demo content
 package: https://github.com/openmrs/openmrs-content-referenceapplication-demo
+
+Generally, the goal is to make the "referenceapplication" content package free from content that an 
+implementation might need to customize and to stick to only core content backing specific things. For example,
+the O3 Login page requires that the "Login Location" tag be available (and associated with at least one 
+location), but locations vary by implementation and even site, so this package just contains the tag.
+Similarly, the Immunization feature requires the CIEL Immunization History concept set to structure obs so
+this is included but the list of immunizations should not be.