make migration interaction diagram use a legend similar to the fediversity interactions diagram

architecture-docs/interactions-migration.mmd

@@ -1,6 +1,6 @@
 flowchart
 
-  user(user) --> |use| deployment
+  user((user)) --> |use| deployment
 
   configuration1 -->|deploy| deployed1
   maintainers --> |maintain| fediversity
@@ -17,13 +17,13 @@ flowchart
     provider-config --> |implement runtime interfaces| configurations1
     subgraph host[runtime environment]
       deployment[applications]
-      state
+      state{state}
     end
   end
 
   deployment --> |store| state
 
-  operator(operator) --> |change| configuration1
+  operator((operator)) --> |change| configuration1
 
   subgraph provider2["fediversity setup B"]
      subgraph configurations2[configurations]
@@ -32,16 +32,16 @@ flowchart
     end
     subgraph host2[runtime environment]
       deployment2[applications]
-      state2[state]
+      state2{state}
     end
   end
 
-  operator --> |trigger| migration
+  operator --> |trigger| migration(migration)
   configurations1 & state --> migration
   migration --> configurations2 & state2
-  provider(hosting provider) --> |maintain| provider1
+  provider((hosting provider)) --> |maintain| provider1
   subgraph fediversity[fediversity source code]
     applications[application modules]
     backends[runtime backends]
-    config[runtime options]
+    config{{runtime options}}
   end