Add PureScript 0.14 migration guide (documentationjs#373)

* Add PureScript 0.14 migration guide

* Add more bifunctor newtypes ported to functors

* Fix small typo in `fromLeft'` example

* Fix typo: use diff syntax highlighter

* Apply suggestions from code review

Co-authored-by: Cyril <[email protected]>

* Apply suggestions from code review

Co-authored-by: Cyril <[email protected]>

* Update ecosystem/purescript-0.14-migration-guide.md

Co-authored-by: Harry Garrood <[email protected]>

* 0.13.x: `a` in `Proxy a` defaults to kind, `Type`

* Note module naming convention for Generic

* Clarify 'this' to mean Proxy type

* Address PR feedback

* Rename ecosystem/purescript-0.14-migration-guide.md to ecosystem/migration-guides/0.14-Migration-Guide.md

* Rename ecosystem/migration-guides/0.14-Migration-Guide.md to migration-guides/0.14-Migration-Guide.md

* Don't mention the deprecated TypeInType Haskell extension

* Fix link to the roles documentation

* Add missing import in examples

* Apply suggestions from code review

Co-authored-by: Harry Garrood <[email protected]>

* Update 0.14-Migration-Guide.md

* Update 0.14-Migration-Guide.md

Co-authored-by: JordanMartinez <[email protected]>
Co-authored-by: Cyril <[email protected]>
Co-authored-by: Harry Garrood <[email protected]>

Author: 4 people