Clarify maximum timeout in Watchdog.md

Apply changes from PR #1134 to v5.13.

Author: Amanda Butler

docs/porting/target/Watchdog.md

@@ -10,7 +10,7 @@ Implement the ResetReason API when implementing the Watchdog API. The ResetReaso
 
 - Sleep and debug modes don't stop the watchdog timer from counting down.
 - The function `hal_watchdog_init` is safe to call repeatedly. The function's implementation must not do anything if `hal_watchdog_init` has already initialized the hardware watchdog timer.
-- Maximum supported timeout is `UINT32_MAX` milliseconds; minimum timeout is 1ms.
+- `UINT32_MAX` milliseconds is the maximum allowed max_timeout `hal_watchdog_get_platform_features()` returns; minimum timeout is 1ms.
 - The watchdog should trigger at or after the timeout value.
 - The watchdog should trigger before twice the timeout value.