Update pcsx2.md

Author: LibretroAdmin

docs/development/cores/core-specific/pcsx2.md

@@ -48,3 +48,12 @@ Enter the following commands (from the PCSX2 source directory):
 
     cmake -B build -G "Visual Studio 17 2022" -DCMAKE_BUILD_TYPE=Release -DLIBRETRO=ON
     cmake --build build --config Release --target pcsx2_libretro
+
+# How to compile (for Linux)
+
+Enter the following commands (from the PCSX2 source directory):
+
+    mkdir build
+    cd build
+    cmake ..
+    make