doc: Update build from source documentation (#1951)

* doc: bring back old build from source instructions

* doc: fix missing ./

* doc: add ./ for windows too

* add cmake prereq

Author: gau-nernst

BUILDING.md

@@ -0,0 +1,111 @@
+# Build Cortex.cpp from source
+
+Firstly, clone the Cortex.cpp repository [here](https://github.com/janhq/cortex.cpp) and initialize the submodules:
+
+```bash
+git clone https://github.com/janhq/cortex.cpp
+cd cortex.cpp
+git submodule update --init --recursive
+```
+
+You also need to install CMake. On Linux and MacOS, you can install CMake via your package manager
+
+```bash
+sudo apt install cmake  # Ubuntu
+brew install cmake  # MacOS
+```
+
+On Windows, you can download CMake from https://cmake.org/download/.
+
+#### Windows
+
+1. Navigate to the `engine` folder.
+2. Configure the vpkg:
+
+```bash
+cd vcpkg
+./bootstrap-vcpkg.bat
+./vcpkg install
+```
+
+3. Build the Cortex.cpp inside the `engine/build` folder (you can change `-DCMAKE_TOOLCHAIN_FILE` to use your own `vcpkg`):
+
+```bash
+mkdir build
+cd build
+cmake .. -DBUILD_SHARED_LIBS=OFF -DCMAKE_TOOLCHAIN_FILE=../vcpkg/scripts/buildsystems/vcpkg.cmake -DVCPKG_TARGET_TRIPLET=x64-windows-static
+cmake --build . --config Release
+```
+
+4. Verify that Cortex.cpp is installed correctly by getting help information.
+
+```sh
+cortex -h
+```
+
+#### Linux and MacOS
+
+1. Navigate to the `engine` folder.
+2. Configure the vpkg:
+
+```bash
+cd vcpkg
+./bootstrap-vcpkg.sh
+./vcpkg install
+```
+
+3. Build the Cortex.cpp inside the `engine/build` folder (you can change `-DCMAKE_TOOLCHAIN_FILE` to use your own `vcpkg`):
+
+```bash
+mkdir build
+cd build
+cmake .. -DCMAKE_TOOLCHAIN_FILE=../vcpkg/scripts/buildsystems/vcpkg.cmake
+make -j4
+```
+
+4. Verify that Cortex.cpp is installed correctly by getting help information.
+
+```sh
+./cortex -h
+```
+
+#### Devcontainer / Codespaces
+
+1. Open Cortex.cpp repository in Codespaces or local devcontainer
+
+    [![Open in GitHub Codespaces](https://github.com/codespaces/badge.svg)](https://codespaces.new/janhq/cortex.cpp?quickstart=1)
+
+    ```sh
+    devcontainer up --workspace-folder .
+    ```
+
+2. Configure vpkg in `engine/vcpkg`:
+
+```bash {"tag": "devcontainer"}
+cd engine/vcpkg
+export VCPKG_FORCE_SYSTEM_BINARIES="$([[ $(uname -m) == 'arm64' ]] && echo '1' || echo '0')"
+./bootstrap-vcpkg.sh
+```
+
+3. Build the Cortex.cpp inside the `engine/build` folder:
+
+```bash {"tag": "devcontainer"}
+cd engine
+mkdir -p build
+cd build
+cmake .. -DCMAKE_TOOLCHAIN_FILE=$(realpath ..)/vcpkg/scripts/buildsystems/vcpkg.cmake
+make -j$(grep -c ^processor /proc/cpuinfo)
+```
+
+4. Verify that Cortex.cpp is installed correctly by getting help information.
+
+```sh {"tag": "devcontainer"}
+cd engine/build
+./cortex -h
+```
+
+5. Everytime a rebuild is needed, just run the commands above using oneliner
+
+```sh
+npx -y runme run --filename README.md -t devcontainer -y
+```

README.md

@@ -160,13 +160,7 @@ cortex-nightly hardware activate
 
 ### Build from Source
 
-```bash
-git clone https://github.com/janhq/cortex.cpp
-cd cortex.cpp
-git submodule update --init --recursive
-cd engine/vcpkg && ./bootstrap-vcpkg.sh
-cd ../build && cmake .. && make -j4
-```
+See [BUILDING.md](BUILDING.md)
 
 ## Uninstall Cortex