Make next minor release: ps-0.13.x-v0.27.4 (#543)

* Remove hanging 'Composition everywhere' line

* Remove 'for web development' part of opening phrase in Preface

* Fix typos in preface

* Remove test accidentally pased into file

* Fix typo

* Replace link with internet archive version

* Remove 'the hard parts of open source' video

* Add link to type system showdown link on discourse

* Rewrite Elm comparsion with PureScript

* Rework PS vs TS section

* Add note: Elm has similar benefits due to type safety

* Add note about OCaml / Reason

* Clean up powerful static type system section

* Clean up immutable persistent data structure section

* Cleanup backends section

* Add caveat about backends current lack of first-class support

* Clean up 'learning curve worth it?' section

* Relocate link to be bottom one in list

* Clean up and shorten responses to various questions

* Clean up opportunity cost section

* Clean up bindings section

* No longer mention pulp + bower possible workflow

* Use full name for slack group

* Clean up function overloading example of bindings tediousness