Add separate README, move the python script, and add note about no_flash commented out lines

Author: will-v-pi

README.md

@@ -203,7 +203,7 @@ App|Description
 [picow_http_client](pico_w/wifi/http_client) | Demonstrates how to make http and https requests
 [picow_http_client_verify](pico_w/wifi/http_client) | Demonstrates how to make a https request with server authentication
 [picow_mqtt_client](pico_w/wifi/mqtt) | Demonstrates how to implement a MQTT client application
-[picow_ota_update](pico_w/wifi/ota_update) | A simple OTA update server (RP235x Only). You can run [python_ota_update.py](pico_w/wifi/python_test_tcp/python_ota_update.py) to upload UF2s to it.
+[picow_ota_update](pico_w/wifi/ota_update) | A minimal OTA update server (RP235x Only). See the separate [README](pico_w/wifi/ota_update/README.md) for more details.
 
 #### FreeRTOS examples
 

pico_w/wifi/ota_update/CMakeLists.txt

@@ -21,6 +21,12 @@ pico_use_wifi_firmware_partition(picow_ota_update)
 
 pico_hash_binary(picow_ota_update)
 pico_sign_binary(picow_ota_update ${CMAKE_CURRENT_LIST_DIR}/private.pem)
+
+# By default this example requires a partition table in flash, and will
+# update the partition that is not currently in use. To use it without
+# a partition table in flash, uncomment the following lines to make it
+# a no_flash binary, so it can update the currently running program.
+
 # pico_set_binary_type(picow_ota_update no_flash)
 # pico_package_uf2_output(picow_ota_update 0x10000000)
 

pico_w/wifi/ota_update/README.md

@@ -0,0 +1,20 @@
+This example requires a partition table in flash. This can be loaded by creating a UF2 from the partition table JSON in this folder:
+```
+picotool partition create main.json pt.uf2
+```
+then dragging & dropping this UF2 onto the device, or loading it using `picotool` and rebooting:
+```
+picotool load pt.uf2
+picotool reboot -u
+```
+
+Once the partition table is loaded, you first need to load the Wi-Fi firmware UF2 (`picow_ota_update_firmware.uf2`) followed by loading & executing the main program (`picow_ota_update.uf2`) - either by dragging and dropping them in order, or using `picotool`:
+```
+picotool load picow_ota_update_firmware.uf2
+picotool load -x picow_ota_update.uf2
+```
+
+Once running, you can use [python_ota_update.py](python_ota_update.py) to upload new UF2s to it using it's IP address:
+```
+python python_ota_update.py 192.168.0.103 picow_ota_update.uf2
+```