Document about Gemfile.lock #768

Before submitting an issue, please be sure to

• Read the contributing instructions
• Update to the latest Gem version (run bundle update github-pages)

This issue affects

• The site generated by GitHub Pages
• Building sites locally

Issue

When you install locally, using bundle install you get one version. And GitHub Pages will always use its own version.

GitHub Pages will never use your Gemfile.lock to resolve dependencies when building your GitHub Pages website.

This fact is important for developers using the pages-gem gem as well as users of GitHub Pages in general.

RELATED: github/gitignore#3690

Follow on work

Add this documentation as justification at: github/gitignore#3690