Update README.md

Add Embox RTOS to the list of supported OSes

README.md

@@ -23,9 +23,11 @@ License 3.0 (Unported) (<http://creativecommons.org/licenses/by-sa/3.0/>).
 
 The official website is [www.libmodbus.org](http://www.libmodbus.org).
 
-The library is written in C and designed to run on Linux, Mac OS X, FreeBSD and
+The library is written in C and designed to run on Linux, Mac OS X, FreeBSD, Embox,
 QNX and Windows.
 
+You can use the library on MCUs with Embox RTOS.
+
 Installation
 ------------
 
@@ -55,6 +57,8 @@ To compile under OS X with [homebrew](http://mxcl.github.com/homebrew/), you
 will need to install the following dependencies first: `brew install autoconf
 automake libtool`.
 
+To build under Embox, you have to use its build system.
+
 Documentation
 -------------