Apps that were created without CLI can be integrated to use CLI later on. This is done by going to the existing app's folder and running
Since the folder structure for an existing app might not follow the same format as one created by the CLI, the
init command has some configuration options.
--source-dir identifies the relative path to the source files (default = src)
--prefix identifies the path within the source dir that Angular application files reside (default = app)
--style identifies the path where additional style files are located (default = css).