add linux build instructions to README.md

Author: aszarth

README.md

@@ -46,6 +46,10 @@ git clone --recursive git@github.com:openmultiplayer/open.mp
 
 Note the use of the `--recursive` argument, because this repository contains submodules.
 
+If you don't use this parameter, you will need to download the files manually and place them in their respective folders, or you will encounter errors during the build process.  
+Submodule folders: `open.mp/libs`, `open.mp/SDK`, `open.mp/SDK/lib`, `open.mp/Shared/Network`
+
+
 ## Building on Windows
 
 ```bash
@@ -70,6 +74,16 @@ cmake -DCMAKE_BUILD_TYPE=Release ..
 make
 ```
 
+## Building on Linux (with Docker)
 
+Replace `/home/user/open.mp` with your actual path in the last command `docker run`
 
+```bash
+cd open.mp
+mkdir build
+cd docker/build_ubuntu-18.04
+docker build -t openmp .
+docker run --rm -ti -v /home/user/open.mp:/omp -w /omp openmp
+```
 
+After that, in `./open.mp/build/Output/Release/Server`, you will find the `omp-server` file and the `components/` folder.