docs: watchdog: codify ident.options as superset of possible status flags

The FIXME comment has been in-tree since the very first git commit.
The described behavior has been since relied on by some userspace, e.g.
the util-linux wdctl command and has been ignored by some kernelspace,
like the f71808e_wdt driver.

The functionality is useful to have to be able to differentiate between a
driver that doesn't support WDIOF_CARDRESET and one that does, but hasn't
had a watchdog reset, thus drop the FIXME to encourage drivers adopting
this convention.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200611191750.28096-2-a.fatoum@pengutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Documentation/watchdog/watchdog-api.rst

@@ -168,7 +168,7 @@ the fields returned in the ident struct are:
 
 the options field can have the following bits set, and describes what
 kind of information that the GET_STATUS and GET_BOOT_STATUS ioctls can
-return.   [FIXME -- Is this correct?]
+return.
 
 	================	=========================
 	WDIOF_OVERHEAT		Reset due to CPU overheat