Expand readme with links and description

BUILD.md

@@ -0,0 +1,33 @@
+# Build instructions
+
+## Windows
+
+Prerequisites:
+- A recent version of Visual Studio 2022 with CMake tools component
+- git
+- Vulkan SDK ([https://vulkan.lunarg.com/](https://vulkan.lunarg.com/)). Don't forget to restart after installing.
+
+Instructions:
+
+1) Run `git clone --recursive https://github.com/cemu-project/Cemu`
+2) Launch `Cemu/build_vs_solution.bat`. If you installed VS to a custom location you may need to manually adjust the path inside the bat file
+3) Wait until done, then open build/Cemu.sln in Visual Studio
+4) Right click 'CemuBin' project -> Set as startup project
+5) Then build the solution and once finished you can run and debug it
+
+You can also skip steps 3-5 and open the root folder of the cloned repo directly in Visual Studio (as a folder) and use the inbuilt cmake support, but be warned that cmake support in VS can be a bit finicky.
+
+## Linux
+
+To compile Cemu, a recent enough compiler and STL with C++20 support is required! We use clang 12, other compilers may work as well.
+
+For ubuntu and most derivatives:
+
+1) Make sure vulkansdk is installed and the VULKAN_SDK environment variable is set correctly.
+2) `sudo apt install -y libgtk-3-dev libsecret-1-dev libgcrypt20-dev libsystemd-dev freeglut3-dev clang-12 nasm`
+3) Run `git clone --recursive https://github.com/cemu-project/Cemu`
+4) `cd Cemu`
+5) `mkdir build && cd build`
+6) `cmake .. -DCMAKE_BUILD_TYPE=release -DCMAKE_C_COMPILER=/usr/bin/clang-12 -DCMAKE_CXX_COMPILER=/usr/bin/clang++-12 -G Ninja -DCMAKE_MAKE_PROGRAM=/usr/bin/ninja`
+
+Build instructions for other distributions will be added in the future!