Update README.md

Author: derzhavin3016

README.md

@@ -1,3 +1,23 @@
 # hSim
 
 Hi there. We introduce high perfomance CPU simulator model.
+
+## How to build
+### Requirements
+* c++20-compatible compiler (tested on clang++ 18.1.3, g++ 13.3.0, but a bit older compilers seems to be ok)
+* CMake 3.19
+* Ruby 3.0
+* Build is tested on Ubuntu 24.04
+
+To build:
+```bash
+cmake -S <path_to_repo_root> -B <path_to_build> [-G Ninja]
+cmake --build <path_to_build> --parallel <amount_of_jobs>
+```
+Ninja is optional, but it looks really pretty
+After build, you can run our simulator and get some help info
+```bash
+./build/hSim --help
+```
+
+