Rename themes -> flavours ? ?

app/javascript/flavours/vanilla/theme.yml

@@ -0,0 +1,33 @@
+#  (REQUIRED) The location of the pack files inside `pack_directory`.
+pack:
+  about: about.js
+  admin:
+  auth:
+  common:
+    filename: common.js
+    stylesheet: true
+  embed: public.js
+  error:
+  home:
+    filename: application.js
+    preload:
+    - features/getting_started
+    - features/compose
+    - features/home_timeline
+    - features/notifications
+  modal:
+  public: public.js
+  settings:
+  share: share.js
+
+#  (OPTIONAL) The directory which contains the pack files.
+#  Defaults to the theme directory (`app/javascript/themes/[theme]`),
+#  but in the case of the vanilla Mastodon theme the pack files are
+#  somewhere else.
+pack_directory: app/javascript/packs
+
+#  (OPTIONAL) By default the theme will fallback to the default theme
+#  if a particular pack is not provided. You can specify different
+#  fallbacks here, or disable fallback behaviours altogether by
+#  specifying a `null` value.
+fallback: