Add instructions to install the oop_build script

install_build_script.md

@@ -5,4 +5,38 @@ title: Install build script - Object-Oriented Programming (5CCYB041)
 
 # How to install the build script used on the OOP course
 
-**TODO**
+The `oop_build` script is already installed on MSYS2 on the KCL systems, and
+included in the MSYS2 ZIP file provided for Windows users (link on the KEATS
+website). You can invoke it simply by typing `oop_build` on the terminal.
+
+It can easily be installed on any other Unix-like system by following these
+instructions. If you're not familiar with this type of operation, we recommend
+you copy/paste the following instructions into a terminal *exactly* as shown
+below, in that order:
+
+1. create the target folder if it doesn't already exist:
+   ```
+   mkdir -p ~/.local/bin
+   ```
+2. download the script to that target folder:
+   ```
+   curl https://raw.githubusercontent.com/jdtournier/simple_build/refs/heads/main/build > ~/.local/bin/oop_build
+   ```
+3. mark the script as executable:
+   ```
+   chmod a+x ~/.local/bin/oop_build
+   ```
+4. add the target folder to your shell startup script if that hasn't already
+   been done:
+   - if you use the `zsh` shell (default on macOS):
+     ```
+     grep -q '^export PATH=~/.local/bin/:' ~/.zshrc || echo 'export PATH=~/.local/bin/:"$PATH"' >> ~/.zshrc
+     ```
+   - if you use the `bash` shell (default on most other Unix systems):
+     ```
+     grep -q '^export PATH=~/.local/bin/:' ~/.bashrc || echo 'export PATH=~/.local/bin/:"$PATH"' >> ~/.bashrc
+     ```
+
+Feel free to modify these instructions to suit your needs if you're comfortable with this.
+
+