Add some comments to python script

Author: MatthijsBurgh

.ci/get_install_build_packages.py

@@ -13,20 +13,24 @@
 system_dir = os.getenv("TUE_SYSTEM_DIR")
 packages = (f.path for f in os.scandir(os.path.join(system_dir, "src")) if f.is_dir())
 
-install_build_pkgs = set()
-build_pkgs = set()
+install_build_pkgs = set()  # All packages that need to be build and require all deps to be installed
+build_pkgs = set()  # All packages that need to be build
 
 for pkg_path in packages:
     pkg = os.path.split(pkg_path)[-1]
+    
+    # Messages need to build and require there depencies
     for msg_type in ["action", "msg", "srv"]:
         if os.path.isdir(os.path.join(pkg_path, msg_type)):
             install_build_pkgs.add(pkg)
             break
 
+    # Pkg with python modules need to build to be added to PYTHONPATH
     if os.path.isfile(os.path.join(pkg_path, "setup.py")):
         catkin_package = catkin_pkg.package.parse_package(
             os.path.join(pkg_path, catkin_pkg.package.PACKAGE_MANIFEST_FILENAME)
         )
+        # If cpp code in pkg, deps need to be installed
         for dep in catkin_package.build_depends:
             if "cpp" in dep.name:  # Might be replaced by a better check to determine their is cpp code in this pkg
                 install_build_pkgs.add(pkg)