add examples

RTL00_SDKV35a/example_sources/pm_deepsleep/readme.txt

@@ -0,0 +1,22 @@
+Example Description
+
+This example describes how to use deep sleep api.
+
+Requirement Components:
+    a LED
+    a push button
+
+Pin name PC_4 and PC_5 map to GPIOC_4 and GPIOC_5:
+ - PC_4 as input with internal pull-high, connect a push button to this pin and ground.
+ - PC_5 as output, connect a LED to this pin and ground.
+
+In this example, LED is turned on after device initialize.
+User push the button to turn off LED and trigger device enter deep sleep mode for 10s.
+If user press any key before sleep timeout, the system will resume.
+LED is turned on again after device initialize.
+
+It can be easily measure power consumption in normal mode and deep sleep mode before/after push the putton.
+
+NOTE: You will see device resume immediately at first time.
+It's because the log uart is a wakeup source and it buffered a wakeup event when DAP is used.
+The symptom won't appear if you use power source on R43 and only power on module.