Update README to include information about CC2531

Author: puddly

README.md

@@ -3,12 +3,10 @@
 [![Build Status](https://travis-ci.org/zha-ng/zigpy-znp.svg?branch=dev)](https://travis-ci.org/zha-ng/zigpy-znp)
 [![Coverage Status](https://coveralls.io/repos/github/zha-ng/zigpy-znp/badge.svg?branch=dev)](https://coveralls.io/github/zha-ng/zigpy-znp?branch=dev)
 
-**[zigpy-znp](https://github.com/zha-ng/zigpy-zhp/)** is a Python library that adds support for common [Texas Instruments ZNP (Zigbee Network Processors)](http://dev.ti.com/tirex/content/simplelink_zigbee_sdk_plugin_2_20_00_06/docs/zigbee_user_guide/html/zigbee/introduction.html) [Zigbee](https://www.zigbee.org) radio modules to [zigpy](https://github.com/zigpy/), a Python Zigbee stack project. 
+**[zigpy-znp](https://github.com/zha-ng/zigpy-zhp/)** is a Python library that adds support for common [Texas Instruments ZNP (Zigbee Network Processors)](http://dev.ti.com/tirex/content/simplelink_zigbee_sdk_plugin_2_20_00_06/docs/zigbee_user_guide/html/zigbee/introduction.html) [Zigbee](https://www.zigbee.org) radio modules to [zigpy](https://github.com/zigpy/), a Python Zigbee stack project.
 
 Together with zigpy and compatible home automation software (namely Home Assistant's [ZHA (Zigbee Home Automation) integration component](https://www.home-assistant.io/integrations/zha/)), you can directly control most Zigbee devices such as Philips Hue, GE, OSRAM LIGHTIFY, Xiaomi/Aqara, IKEA Tradfri, Samsung SmartThings, and many more.
 
-This zigpy-znp library allows Zigpy to interact with Texas Instruments ZNP (Zigbee Network Processor) coordinator firmware via TI Z-Stack Monitor and Test(MT) APIs using an UART/serial interface. Radio module hardware compatible include but is possibly not limited to Texas Instruments CC13x2 and CC26x2R based chips flashed with Z-Stack 3.x coordinator firmware.
-
 # Installation
 Install the Python module within your virtual environment:
 
@@ -22,7 +20,7 @@ If you are using Home Assistant, copy `custom_components/custom_zha_radios.py` i
 custom_zha_radios:
  znp:
    module: zigpy_znp.zigbee.application
-   description: TI CC13x2, CC26x2, and ZZH
+   description: TI CC13x2, CC26x2, ZZH, and CC2531
 ```
 
 # Configuration
@@ -51,12 +49,13 @@ Tested migrations:
  - LAUNCHXL-CC26X2R1 running 3.30.00.03 to and from the zig-a-zig-ah! running 4.10.00.78.
 
 # Hardware requirements
-USB-adapters, GPIO-modules, and development-boards running recent TI Z-Stack releases (i.e. CC13x2 and CC26x2) are supported. Reference hardware for this project includes:
+USB-adapters, GPIO-modules, and development-boards running recent TI Z-Stack releases (above version 3.0.0) are supported. Reference hardware for this project includes:
 
- - [TI LAUNCHXL-CC26X2R1](https://www.ti.com/tool/LAUNCHXL-CC26X2R1) running [Z-Stack 3.30.00.03](https://github.com/Koenkk/Z-Stack-firmware/tree/master/coordinator/Z-Stack_3.x.0/bin). You can flash `CC26X2R1_20191106.hex` using [TI's UNIFLASH](https://www.ti.com/tool/download/UNIFLASH).
- - [Electrolama's zig-a-zig-ah!](https://electrolama.com/projects/zig-a-zig-ah/) running [Z-Stack 4.10.00.78](https://github.com/Koenkk/Z-Stack-firmware/tree/develop/coordinator/Z-Stack_3.x.0/bin). You can flash `CC26X2R1_20200417.hex` using [cc2538-bsl](https://github.com/JelmerT/cc2538-bsl).
+ - (**STABLE**) [TI LAUNCHXL-CC26X2R1](https://www.ti.com/tool/LAUNCHXL-CC26X2R1) running [Z-Stack 3.30.00.03](https://github.com/Koenkk/Z-Stack-firmware/tree/master/coordinator/Z-Stack_3.x.0/bin). You can flash `CC26X2R1_20191106.hex` using [TI's UNIFLASH](https://www.ti.com/tool/download/UNIFLASH).
+ - (**STABLE**) [Electrolama's zig-a-zig-ah!](https://electrolama.com/projects/zig-a-zig-ah/) running [Z-Stack 4.10.00.78](https://github.com/Koenkk/Z-Stack-firmware/tree/develop/coordinator/Z-Stack_3.x.0/bin). You can flash `CC26X2R1_20200417.hex` using [cc2538-bsl](https://github.com/JelmerT/cc2538-bsl).
+ - (**ALPHA**) CC2531 running [Z-Stack 3.0.1](https://github.com/Koenkk/Z-Stack-firmware/blob/master/coordinator/Z-Stack_3.0.x/bin/CC2531_20190425.zip). You can flash `CC2531ZNP-without-SBL.bin` to your stick directly with `zigpy_znp`: `python -m zigpy_znp.tools.flash_write -i /path/to/CC2531ZNP-without-SBL.bin /dev/serial/by-id/YOUR-CC2531`.
 
-Z-Stack versions 3.x and above are currently required and all communication with the radio module is done over the the Z-Stack Monitor and Test (MT) interface via a serial port.
+Older versions of Z-Stack are not currently supported. Z-Stack versions 3.x and above are currently required and all communication with the radio module is done over the the Z-Stack Monitor and Test (MT) interface via a serial port.
 
 ## Texas Instruments Chip Part Numbers
 Texas Instruments (TI) has quite a few different wireless MCU chips and they are all used/mentioned in open-source Zigbee world which can be daunting if you are just starting out. Here is a quick summary of part numbers and key features.