When updating the boilerplate for CLI-based docs examples, one needed to
install dependencies inside the
`aio/tools/examples/shared/boilerplate/cli/` directory, which resulted
in a `node_modules/` directory and a `yarn.lock` file. These were not
supposed to be part of the boilerplate, so they had to be manually
removed after the boilerplate was updated.
This commit simplifies the workflow by allowing boilerplate files to be
ignored (both by git and the `example-boilerplate.js` script) via a
`.gitignore` file. This way, it is no longer necessary to manually
remove the unneeded directories/files.
PR Close#38992
Derek Cormier