Update remote theme instructions

[susanstevens]

This is a documentation change.

Summary

Update remote theme installation instructions to indicate that jekyll-include-cache should be added to the Gemfile.

Context

I followed the remote theme installation instructions and got the following error when running bundle exec jekyll serve:

Dependency Error: Yikes! It looks like you don't have jekyll-include-cache or one of its dependencies installed. In order to use Jekyll as currently configured, you'll need to install this gem. The full error message from Ruby is: 'cannot load such file -- jekyll-include-cache' If you run into trouble, you can find helpful resources at https://jekyllrb.com/help/! 

Adding the jekyll-include-cache gem to my Gemfile resolved the error, so it should probably be part of the instructions.

[iBug]

This may not be necessary as the next point says:

2. Add jekyll-include-cache to the plugins array of your _config.yml.

[susanstevens]

@iBug I thought calling out that you need to add jekyll-include-gem to the Gemfile would be helpful since step 2 only mentions adding it to _config.yml. I had to add it the Gemfile and add it to the plugins array in _config.yml.

[iBug]

Shouldn't be like that... The gem is included with github-pages and adding it in _config.yml should suffice.

Additionally, appending group: :jekyll_plugins in Gemfile is equivalent to adding it in the config (with higher priority), so if the "canonical" way doesn't work for you, perhaps you should double-check your config for typos or such?

[akhyarrh]

Shouldn't be like that... The gem is included with github-pages and adding it in _config.yml should suffice.

AFAIK, jekyll-include-cache is not included in github-pages gem: https://pages.github.com/versions/

jekyll-include-cache are added by theme: https://github.com/mmistakes/minimal-mistakes/blob/master/minimal-mistakes-jekyll.gemspec#L23

But maybe it will not loaded if theme is used via remote_theme, so that why Jekyll cant find jekyll-include-cache ?

[mmistakes]

I believe @susanstevens and @akhyarrh are correct. jekyll-include-cache isn't a dependency of the GitHub Pages gem and needs to be included in the Gemfile to work.

The plugin is whitelisted to work on GitHub Pages, but it's not activated by default.