Fix plugs/slots definitions

Related to jreleaser/jreleaser#1686

Author: aalmiray

docs/modules/reference/pages/packagers/snap.adoc

@@ -135,24 +135,26 @@ include::partial$packagers/yaml/package-name.adoc[]
     # Allows plugs to be configured.
     # icon:dot-circle[]
     plugs:
-      some_plug_name:
-        key: value
-        reads:
-        - $HOME/.foo
-        writes:
-        - $HOME/.foo
-        - $HOME/.foobar
+      - some_plug_name:
+          attributes:
+            key: value
+          reads:
+          - $HOME/.foo
+          writes:
+          - $HOME/.foo
+          - $HOME/.foobar
 
     # Allows slots to be configured.
     # icon:dot-circle[]
     slots:
-      some_slot_name:
-        key: value
-        reads:
-        - $HOME/.foo
-        writes:
-        - $HOME/.foo
-        - $HOME/.foobar
+      - some_slot_name:
+          attributes:
+            key: value
+          reads:
+          - $HOME/.foo
+          writes:
+          - $HOME/.foo
+          - $HOME/.foobar
 
     # Configures build/run architectures
     # More details can be found at link:https://snapcraft.io/docs/architectures[]