Update toc.html from allejo/jekyll-toc:master (#2355)

Update jekyll-toc to v1.0.5

Update jekyll-toc with heading classes fix (#1337)

Merge branch 'master' of https://github.com/mmistakes/minimal-mistakes

# Conflicts:
#	docs/_docs/18-history.md

Toggle table of contents via front matter (#1310)

* Add jekyll-toc include
* Reduce whitespace generated by comments
* Add table of contents include to `single` layout
* Replace `toc` include with jekyll-toc enabled YAML Front Matter
* Update README
* Update table of contents documentation
  - Revise `toc` helper include to mention that it will be deprecated in the next major version.
  - Add documentation to `single` layout explaining how to enable table of contents on those pages.
* Update CHANGELOG and history
* Update LICENSE

Close #1222 

Merge branch 'feature/refactor-layouts' into develop

Improve table of contents
- Replace html snippet with _includes/toc.html
- Add FA icon to table of contents header
- Display table of contents on small screens
- Add hierarchy to toc with indents