📝 Update docs in README

Author: foosel

README.md

@@ -4,7 +4,12 @@ The Firmware Check plugin tries to identify printers or rather printer firmware
 disabled thermal runaway protection, or other kinds of severe issues, like known communication crippling bugs, and
 displays a warning box to logged in users on identification of such a firmware.
 
-![Screenshot](https://raw.githubusercontent.com/OctoPrint/OctoPrint-FirmwareCheck/master/extras/screenshot.png)
+![Screenshot of two warnings](https://raw.githubusercontent.com/OctoPrint/OctoPrint-FirmwareCheck/master/extras/screenshot.png)
+
+Since version 2021-2-4 it also displays info/"heads-ups" messages if a development firmware build
+is detected. This kind of message can be disabled.
+
+![Screenshot of an info](https://raw.githubusercontent.com/OctoPrint/OctoPrint-FirmwareCheck/master/extras/screenshot2.png)
 
 It was formerly called "Printer Safety Check" and used to be bundled with OctoPrint since version
 1.3.7. It was unbundled in 1.4.1 and turned into an install dependency to allow for a separate release cycle. It is
@@ -45,8 +50,9 @@ Payload:
 
 ## Detected issues
 
-The plugin currently issues two types of warnings: `firmware-unsafe` for firmware known to have severe safety issues
-and `firmware-broken` for firmware known to have a broken implementation of the communication protocol.
+The plugin currently issues three types of warnings: `firmware-unsafe` for firmware known to have severe safety issues,
+`firmware-broken` for firmware known to have a broken implementation of the communication protocol
+and `firmware-development` for detected development builds of firmware.
 
 ### Unsafe firmware
 
@@ -65,3 +71,7 @@ for a list of currently known to be affected printers.
 Please refer to the [entry on the this warning in OctoPrint's FAQ](https://faq.octoprint.org/warning-firmware-broken-creality-temp)
 for variants of this and a list of currently known to be affected printers.
 
+### Development firmware
+
+Please refer to the [entry on the "development firmware" warning in OctoPrint's FAQ](https://faq.octoprint.org/warning-firmware-development)
+for a list of currently detected firmware variants.