[PATCH] wic/help.py: document requirements for valid fstab generation

[Joshua Lock <joshua.g.lock@intel.com>]

Without one of the --ondrive, --ondisk or --use-uuid options for a
partition with a mountpoint specified the automatically generated
fstab entry will be invalid.

[YOCTO #8844]

Signed-off-by: Joshua Lock <joshua.g.lock@intel.com>
---
 scripts/lib/wic/help.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/scripts/lib/wic/help.py b/scripts/lib/wic/help.py
index be334e7..f5587bb 100644
--- a/scripts/lib/wic/help.py
+++ b/scripts/lib/wic/help.py
@@ -629,6 +629,13 @@ DESCRIPTION
        If a <mountpoint> is not specified the partition will be created
        but will not be mounted.
 
+       Partitions with a <mountpoint> specified will be automatically mounted.
+       This is achieved by wic adding entries to the fstab during image
+       generation. In order for a valid fstab to be generated one of the
+       --ondrive, --ondisk or --use-uuid partition options must be used for
+       each partition that specifies a mountpoint.
+
+
        The following are supported 'part' options:
 
          --size: The minimum partition size. Specify an integer value
-- 
2.5.0