Add the documentation to avoid a warning with 'make htmldocs'.
Fixes: 10107efedd5 ("sandbox: add SIGALRM-based watchdog device")
Signed-off-by: Simon Glass <sjg at chromium.org>
---
include/os.h | 4 ++++
1 file changed, 4 insertions(+)
Applied to u-boot-dm, thanks!