Add ResetReason and Watchdog driver docs

docs/reference/api/drivers/ResetReason.md

@@ -0,0 +1,39 @@
+## ResetReason
+
+Use the ResetReason interface to access hardware reset reason registers in a portable fashion.
+
+### ResetReason class reference
+
+[![View code](https://www.mbed.com/embed/?type=library)](http://os-doc-builder.test.mbed.com/docs/v5.8/mbed-os-api-doxy/classmbed_1_1_resetreason.html)
+
+### ResetReason example
+
+```c++
+#include "mbed.h"
+#include "ResetReason.h"
+
+#include <string>
+
+std::string reset_reason_to_string(const reset_reason_t reason)
+{
+ switch (reason)
+ {
+ case RESET_REASON_POWER_ON:
+ return "Power On";
+ case RESET_REASON_PIN_RESET:
+ return "Hardware Pin";
+ case RESET_REASON_SOFTWARE:
+ return "Software Reset";
+ case RESET_REASON_WATCHDOG:
+ return "Watchdog";
+ default:
+ return "Other Reason";
+ }
+}
+
+int main() {
+ const reset_reason_t reason = ResetReason::get();
+
+ printf("Last system reset reason: %s\n", reset_reason_to_string(reason).c_str());
+}
+```

docs/reference/api/drivers/Watchdog.md

@@ -1,11 +1,40 @@
 ## Watchdog
 
-[Add description here.]
+Use the Watchdog interface to set up a hardware watchdog that resets the system after a set period of time if you do not periodically refresh it before it expires.
+
+<span class="notes">**Note:** The maximum amount of time that you can set as the Watchdog timeout varies depending on the target hardware. You can check the maximum value by calling `Watchdog::max_timeout()`.</span>
 
 ### Watchdog class reference
 
-[Add class reference here. Ask your editor for help if you've never done this before.]
+[![View code](https://www.mbed.com/embed/?type=library)](http://os-doc-builder.test.mbed.com/docs/v5.8/mbed-os-api-doxy/classmbed_1_1_watchdog.html)
 
 ### Watchdog example
 
-[Add example here.]
+Create a watchdog timer that expires after 5 seconds and that you refresh by pushing BUTTON1 on the target board.
+
+```c++
+#include "mbed.h"
+
+#include "InterruptIn.h"
+#include "mbed_sleep.h"
+#include "Watchdog.h"
+
+mbed::InterruptIn button(BUTTON1);
+mbed::Watchdog watchdog;
+
+void trigger()
+{
+ printf("Refreshing watchdog timer\r\n");
+ watchdog.kick();
+}
+
+int main()
+{
+ printf("Board started, Watchdog timer initialized to 5 seconds.\r\n");
+ watchdog.start(5000);
+
+ button.rise(&trigger);
+
+ sleep();
+}
+```