README.profile.rst: document %ARCHISO_UUID% and %ARCHISO_SEARCH_FILENAME%

While their values are not affected by `profiledef.sh` variables, there
is no other place to document these *identifiers*.

1 files changed, 6 insertions, 0 deletions

diff --git a/docs/README.profile.rst b/docs/README.profile.rst
index f1fd717..0b5041a 100644
--- a/docs/README.profile.rst
+++ b/docs/README.profile.rst
@@ -140,6 +140,12 @@ respective variables in ``profiledef.sh``:
 * ``%INSTALL_DIR%``: Set this using the ``install_dir`` variable in ``profiledef.sh``.
 * ``%ARCH%``: Set this using the ``arch`` variable in ``profiledef.sh``.
 
+Additionally there are also *custom template identifiers* have harcoded values set by ``mkarchiso`` that cannot be
+overridden:
+
+* ``%ARCHISO_UUID%``: the ISO 9660 modification date in UTC, i.e. its "UUID",
+* ``%ARCHISO_SEARCH_FILENAME%``: file path on ISO 9660 that can be used by GRUB to find the ISO volume
+  (**for GRUB ``.cfg`` files only**).
 
 efiboot
 -------