adding dconf doc

docs/howto/manage-dconf-settings.md

@@ -0,0 +1,24 @@
+# Manage dconf settings
+
+Here is an example (thanks [@gmvelencoso](https://github.com/gmvelencoso)) 
+using dotdrop to manage dconf settings:
+
+```yaml
+actions:
+  dconf_load: dconf load "{0}" < "{{@@ _dotfile_abs_src @@}}"
+trans_update:
+  dconf_dump: dconf dump "{2}" > "{1}"
+dconf_tilix:
+    src: config/tilix/tilix.dconf
+    dst: /tmp/tilix.dconf 
+    actions:
+      - dconf_load /com/gexperts/Tilix/
+    trans_update: dconf_dump /com/gexperts/Tilix/
+    link: nolink
+````
+
+On `install`/`compare`, the [action](../config/config-actions.md) `dconf_load` will call `dconf` to load
+the configuration from the file stored in the *dotpath* under `config/tilix/tilix.dconf`.
+
+On `update`, the [transformation](../config/config-transformations.md) `trans_update` will dump the configuration
+entry and use it to update the file in the *dotpath*.