diff --git a/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst b/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst
index ad8143711..d9b7492b9 100644
--- a/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst
+++ b/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst
@@ -593,6 +593,9 @@ These files are written in the JSON file format and are stored in a
       variables to include in :term:`BB_ENV_PASSTHROUGH_ADDITIONS`.
 
    -  ``bb-layers`` (*optional*): Layers to add to the ``bblayers.conf`` file.
+      If the path starts by ``{THISDIR}/``, it will be relative to the directory
+      containing the configuration file. If not, it will be relative to the
+      directory used by ``bitbake-setup`` to store the sources.
       This cannot be used in conjunction with the ``oe-template`` option.
 
    -  ``oe-template`` (*optional*, OpenEmbedded specific): OpenEmbedded template