upgrade guide

README.md

@@ -126,13 +126,23 @@ info.
 
 ## Adapting an existing ontology repo
 
-The OSK is designed for creating a new repo for a new ontology. It can still be used to help figure out how to migrate an existing github repository to the OSK structure. There are different ways to do this.
+The ODK is designed for creating a new repo for a new ontology. It can still be used to help figure out how to migrate an existing github repository to the OSK structure. There are different ways to do this.
 
  * Manually compare your ontology against the [template](https://github.com/INCATools/ontology-starter-kit/tree/master/template) folder and make necessary adjustments
  * Run osk as if creating a new repo. Manually compare this with your existing repo and use `git mv` to rearrange, and adding any missing files by copying them across and doing a `git add`
  * Create a new repo de novo and abandon your existing one, using github issue mover to move tickets across.
 
- Obviously the second method is not ideal as you lose your github history. Note even with `git mv` history tracking becomes harder
+Obviously the second method is not ideal as you lose your github history. Note even with `git mv` history tracking becomes harder
+
+If you have built your ontology using a previous version of ODK,
+migration of your setup is unfortunately a manual process. In general
+you do not absolutely *need* to upgrade your setup, but doing so will
+bring advantages in terms of aligning with emerging standards ways of
+doing things. The less customization you do on your repo the easier it
+should be to migrate.
+
+Consult the [Changes.md](Changes.md) file for changes made between
+releases to assist in upgrading.
 
 ## More documentation