* fix: Add "boolean" and "symbol" types for "key" attribute. (#2614)

Booleans as keys are supported since v2.4.2 and symbols since v2.5.12.

* docs: update ben's info (#2619)

* chore: update sponsor link

* chore: update sponsor

* chore: update ad code

* chore: update sponsors (#2651)

* feature: add option for docs-next in guide (#2644)

* add option for next in guide

* docs: update version label

Co-authored-by: Ben Hong <ben@bencodezen.io>

* [automated] Patreon sponsors update (#2658)

* chore: update sponsors

* Update _config.yml

* Update _config.yml

Co-authored-by: Evan You <yyx990803@gmail.com>

* docs: update testing section with more comprehensive guidance (#2654)

* chore: update sponsors (#2660)

* docs: fixed profile images of Jos Gerards, Vincent Mayers, Luke Thomas

* Add flatlogic themes (#2669)

* docs: adds warning to vm.$slots that slots are not reactive (#2663)

* Add non-reactivity warning to vm.$slots

* Fix deleted content

* chore: update sponsors (#2680)

* docs: properly order words in component name (#2683)

https://vuejs.org/v2/style-guide/#Order-of-words-in-component-names-strongly-recommended

* chore: update sponsors (#2681)

* translated all new docs

* fixed the tip format

* Apply suggestions from code review

Co-authored-by: GU Yiling <justice360@gmail.com>

* Update testing.md

* Update testing.md

* Update testing.md

Co-authored-by: Mariusz Pawelski <mariusz.pawelski@gmail.com>
Co-authored-by: Ben Hong <ben@bencodezen.io>
Co-authored-by: Evan You <yyx990803@gmail.com>
Co-authored-by: vue-bot <bot@vuejs.org>
Co-authored-by: Acidiney Dias <acidineydias@gmail.com>
Co-authored-by: Tola <tolasann@gmail.com>
Co-authored-by: shoudaos <shoudaos92@gmail.com>
Co-authored-by: tessaSAC <tessaSAC@users.noreply.github.com>
Co-authored-by: Dmitriy Aleksandrovich <gormonn@rambler.ru>
Co-authored-by: GU Yiling <justice360@gmail.com>