docs: create linux-build.sh reference for custom build

Author: lumirlumir

docs/linux-build.sh

@@ -0,0 +1,15 @@
+sudo apt update -y
+sudo apt install -y git python3 g++ cmake ninja-build
+
+# Replace llvmorg-18.1.8 with your desired version. Check the tags at https://github.com/llvm/llvm-project/tags
+git clone --depth 1 --branch llvmorg-18.1.8 https://github.com/llvm/llvm-project.git
+cd llvm-project
+
+cmake -S llvm -B build-linux-x64 -G Ninja \
+  -DLLVM_ENABLE_PROJECTS="clang" \
+  -DCMAKE_BUILD_TYPE=MinSizeRel \
+
+ninja -C build clang-format
+
+# Check clang-format version
+build/bin/clang-format --version