documentation: add build status badges

Author: kolomenkin

README.md

@@ -1,4 +1,4 @@
-# Key-Value Web Server
+# Key-Value Web Server [![Code license](https://img.shields.io/github/license/work-examples/key-value-web-server)](LICENSE)
 
 An HTTP web server with a REST API for persistent key-value storage.
 Collects read-write statistics for the entire storage and for each key.
@@ -8,6 +8,11 @@ Collects read-write statistics for the entire storage and for each key.
 **Software requirements**: `CMake 3.2+`, C++17 compatible compiler, `Python 3.7+`  
 **Operation systems**: `Windows`, `Linux`, `macOS`
 
+| Branch      | CI Build Status                                                                                                                                                                                                 |
+|-------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| **master**  | [![CI status](https://github.com/work-examples/key-value-web-server/actions/workflows/build_cmake.yml/badge.svg?branch=master)](https://github.com/work-examples/key-value-web-server/actions?query=branch%3Amaster)   |
+| **develop** | [![CI status](https://github.com/work-examples/key-value-web-server/actions/workflows/build_cmake.yml/badge.svg?branch=develop)](https://github.com/work-examples/key-value-web-server/actions?query=branch%3Adevelop) |
+
 ## Test Task Description
 
 You need to write two applications, a client and a server, that communicate with each other.