[FIX] getting_started: invalid addons-path

The "../technical-training-sandbox" is added too early in the path since
its still empty, and results into an "invalid addons-path" error.

Part-of: odoo/documentation#6607

content/developer/tutorials/getting_started/02_setup.rst

@@ -74,7 +74,7 @@ interface of the server.
 .. code-block:: console
 
     $ cd $HOME/src/odoo/
-    $ ./odoo-bin --addons-path="addons/,../enterprise/,../technical-training-sandbox" -d rd-demo
+    $ ./odoo-bin --addons-path="addons/,../enterprise/" -d rd-demo
 
 There are multiple :ref:`command-line arguments <reference/cmdline/server>` that you can use to run
 the server. In this training you will only need some of them.
@@ -118,6 +118,10 @@ the server. In this training you will only need some of them.
      - :option:`-u <odoo-bin --update>`: Update some modules before running the server
        (comma-separated list).
 
+.. note::
+   For now you cannot add `../technical-training-sandbox` to your `addons-path` as it is empty
+   and will result into an invalid addons-path folder error, but you will have to add it back later on !
+
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