new: doc: [opensem] add some `README.org` information

README.org

@@ -0,0 +1,6 @@
+# -*- ispell-local-dictionary: "english" -*-
+
+* What is jev-charms
+
+This contains the 0k charm recipes for a managed deployment of ~opensem~
+app on a 0k ready installation.

opensem/README.org

@@ -3,11 +3,8 @@
 
 * Build source code
 
-Using a ~Dockerfile~ and forcing latest known working ~composer.lock~
-and ~yarn.lock~ to ensure reproducible build.
-
-We provide the resulting production ready application files in a
-~tar.xz~.
+Using ~opensem~ source code, with the ~./build.sh~, we can build a proper
+~opensem-X.Y.Z.tar.xz~ that is ready for deployment.
 
 * Charm usage
 
@@ -17,3 +14,62 @@ provides this relation.
 
 So you need to explicitly express this relation to a =stub= service.
 
+* Usage
+
+** Opensem
+
+Typical installation of opensem would be:
+
+#+begin_src yaml
+opensem:
+  charm: opensem
+  options:
+    env:
+      mail:
+        from:
+          name: "Boutique Jardin En Vie"
+          address: boutique@jardinenvie.com
+
+  relations:
+    publish-dir:
+      frontend:
+        domain: boutique.jardinenvie.com
+    paybox-system:
+      paybox:
+        test: true
+        rank: "001"  ## keep the double-quotes !
+        site: 2XXXX9
+        id: 2XXXXX4
+        hmac-key: "FFAXXXXX...XXXXX"
+
+paybox:
+  charm: stub
+
+letsencrypt:
+  options:
+    email: my-email@example.com
+
+frontend:
+  charm: mailcow-www
+
+logrotate:
+
+cron:
+
+jev-smtp:
+  charm: smtp-stub
+  options:
+    host: mail.jardinenvie.com
+    port: 465
+    connection-security: ssl
+    auth-method: password
+    login: boutique@jardinenvie.com
+    password: CXXXXXXXXXXg
+
+rsync-backup:
+  options:
+    ident: ext-00.jardinenvie.com
+    target: my-backup-host.com
+    private-key: |
+      # ...
+#+end_src