Documentation: Capitalize Fahrenheit in watchdog-api.rst

Capitalize "fahrenheit," a spelling mistake.
Signed-off-by: David Hunter <david.hunter.linux@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240807185332.61624-1-david.hunter.linux@gmail.com

Documentation/watchdog/watchdog-api.rst

@@ -249,7 +249,7 @@ Note that not all devices support these two calls, and some only
 support the GETBOOTSTATUS call.
 
 Some drivers can measure the temperature using the GETTEMP ioctl.  The
-returned value is the temperature in degrees fahrenheit::
+returned value is the temperature in degrees Fahrenheit::
 
     int temperature;
     ioctl(fd, WDIOC_GETTEMP, &temperature);