Merge branch 'stylelint-plus-prettier' of github.com:pmarsceill/just-the-docs into stylelint-plus-prettier

v0.2.8

bugfix in search.rake

Update rake requirement from ~> 12.3.1 to >= 12.3.1, < 13.1.0

Bump stylelint-config-primer from 8.0.0 to 9.0.0

Update bundler requirement from ~> 2.0.1 to ~> 2.1.4