Add more instructions to Xcode setup (#5757)

Summary:
I ran into the following error during `Build Cmake Dependencies` phase:

```
cmake not found, please install cmake.
```

It was not clear how to install cmake. This PR adds the following instructions:

```
cmake not found, please install cmake.
1. Download Cmake.app from https://cmake.org/download with version > 3.19.
2. Install it to Applications/ folder and run sudo /Applications/CMake.app/Contents/bin/cmake-gui --install to install CMake commandline tools.
```

<img width="1130" alt="Screenshot 2024-09-30 at 9 46 04 AM" src="https://github.com/user-attachments/assets/3aa220c6-27da-4b8d-a7b0-3bd2f8e6b5a3">

Pull Request resolved: #5757

Reviewed By: shoumikhin

Differential Revision: D63643170

Pulled By: larryliu0820

fbshipit-source-id: c565a0f1d9e0001e9b43cac4e68e64d270f48018

Author: larryliu0820

examples/demo-apps/apple_ios/LLaMA/LLaMA.xcodeproj/project.pbxproj

@@ -630,7 +630,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "set -e\n\nif ! command -v cmake &> /dev/null\nthen\n    echo \"cmake not found, please install cmake.\"\n    exit 1\nfi\n\nCMAKE_DIR=\"$TEMP_DIR/cmake\"\nrm -rf \"$CMAKE_DIR\"\n\nPLATFORM=\"SIMULATORARM64\"\nDEPLOYMENT_TARGET=\"17.0\"\n\nif [[ \"$PLATFORM_NAME\" == *\"iphoneos\"* ]]; then\n  PLATFORM=\"OS64\"\nelif [[ \"$PLATFORM_NAME\" == *\"macos\"* ]]; then\n  PLATFORM=\"MAC_ARM64\"\n  DEPLOYMENT_TARGET=\"10.15\"\nfi\n\ncmake_build() {\n    local src_dir=$1\n    shift\n    local extra_args=(\"$@\")\n    local build_dir=\"$CMAKE_DIR/build/$(basename \"$src_dir\")\"\n\n    mkdir -p \"$build_dir\" && cd \"$build_dir\"\n    cmake -G Xcode \\\n          -DCMAKE_BUILD_TYPE=\"Release\" \\\n          -DCMAKE_CXX_STANDARD=17 \\\n          -DCMAKE_TOOLCHAIN_FILE=\"$SRCROOT/../../../../third-party/ios-cmake/ios.toolchain.cmake\" \\\n          -DCMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD=\"c++17\" \\\n          -DCMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY=\"libc++\" \\\n          -DPLATFORM=\"$PLATFORM\" \\\n          -DDEPLOYMENT_TARGET=\"$DEPLOYMENT_TARGET\" \\\n          \"${extra_args[@]}\" \\\n          \"$src_dir\"\n    cmake --build . --config \"Release\"\n    cmake --install . --prefix \"$CMAKE_DIR\"\n}\n\ncmake_build \"$SRCROOT/../../../../extension/llm/third-party/abseil-cpp\" \\\n    -DABSL_PROPAGATE_CXX_STD=ON\n\ncmake_build \"$SRCROOT/../../../../extension/llm/third-party/re2\" \\\n    -DCMAKE_PREFIX_PATH=\"$CMAKE_DIR/lib/cmake/absl\"\n    \ncmake_build \"$SRCROOT/../../../../extension/llm/third-party/sentencepiece\" \\\n    -DSPM_ENABLE_SHARED=OFF\n\necho \"$(find $CMAKE_DIR/lib -name \"*.a\" | sed -E 's|^.*/lib([^/]+)\\.a|-l\\1|g' | tr '\\n' ' ')\" > \"$CMAKE_DIR/linker_flags\"\n";
+			shellScript = "set -e\n\nif ! command -v cmake &> /dev/null\nthen\n    echo \"cmake not found, please install cmake. \\n1. Download Cmake.app from https://cmake.org/download with version > 3.19. \\n2. Install it to Applications/ folder and run sudo /Applications/CMake.app/Contents/bin/cmake-gui --install to install CMake commandline tools.\"\n    exit 1\nfi\n\nCMAKE_DIR=\"$TEMP_DIR/cmake\"\nrm -rf \"$CMAKE_DIR\"\n\nPLATFORM=\"SIMULATORARM64\"\nDEPLOYMENT_TARGET=\"17.0\"\n\nif [[ \"$PLATFORM_NAME\" == *\"iphoneos\"* ]]; then\n  PLATFORM=\"OS64\"\nelif [[ \"$PLATFORM_NAME\" == *\"macos\"* ]]; then\n  PLATFORM=\"MAC_ARM64\"\n  DEPLOYMENT_TARGET=\"10.15\"\nfi\n\ncmake_build() {\n    local src_dir=$1\n    shift\n    local extra_args=(\"$@\")\n    local build_dir=\"$CMAKE_DIR/build/$(basename \"$src_dir\")\"\n\n    mkdir -p \"$build_dir\" && cd \"$build_dir\"\n    cmake -G Xcode \\\n          -DCMAKE_BUILD_TYPE=\"Release\" \\\n          -DCMAKE_CXX_STANDARD=17 \\\n          -DCMAKE_TOOLCHAIN_FILE=\"$SRCROOT/../../../../third-party/ios-cmake/ios.toolchain.cmake\" \\\n          -DCMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD=\"c++17\" \\\n          -DCMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY=\"libc++\" \\\n          -DPLATFORM=\"$PLATFORM\" \\\n          -DDEPLOYMENT_TARGET=\"$DEPLOYMENT_TARGET\" \\\n          \"${extra_args[@]}\" \\\n          \"$src_dir\"\n    cmake --build . --config \"Release\"\n    cmake --install . --prefix \"$CMAKE_DIR\"\n}\n\ncmake_build \"$SRCROOT/../../../../extension/llm/third-party/abseil-cpp\" \\\n    -DABSL_PROPAGATE_CXX_STD=ON\n\ncmake_build \"$SRCROOT/../../../../extension/llm/third-party/re2\" \\\n    -DCMAKE_PREFIX_PATH=\"$CMAKE_DIR/lib/cmake/absl\"\n    \ncmake_build \"$SRCROOT/../../../../extension/llm/third-party/sentencepiece\" \\\n    -DSPM_ENABLE_SHARED=OFF\n\necho \"$(find $CMAKE_DIR/lib -name \"*.a\" | sed -E 's|^.*/lib([^/]+)\\.a|-l\\1|g' | tr '\\n' ' ')\" > \"$CMAKE_DIR/linker_flags\"\n";
 		};
 /* End PBXShellScriptBuildPhase section */