Docs: init empty migration guide with references

docs/mkdocs.yml

@@ -71,6 +71,7 @@ nav:
           - Testing: contributing/testing.md
       - Repo Layout: manual/repo-layout.md
       - Migrate existing Flakes: manual/migration-guide.md
+      - Migrate inventory Services: guides/migrate-inventory-services.md
   - Reference:
       - Overview: reference/index.md
       - Clan Modules:

docs/site/guides/migrate-inventory-services.md

@@ -0,0 +1,7 @@
+# How to migrate `Inventory.services`
+
+## Further reference
+
+- [Authoring a 'clan.service' module](../authoring/clanServices/index.md)
+- [Setting up `inventory.instances`](../manual/distributed-services.md)
+- [Inventory Reference](../reference/nix-api/inventory.md)

docs/site/manual/distributed-services.md

@@ -1,8 +1,10 @@
-# Instances
+# Setting up `inventory.instances`
+
+In Clan *distributed services* can be declaratively deployed using the `inventory.instances` attribute
 
 First of all it might be needed to explain what we mean by the term *distributed service*
 
-## What is considered a service?
+## What is considered a distributed service?
 
 A **distributed service** is a system where multiple machines work together to provide a certain functionality, abstracting complexity and allowing for declarative configuration and management.