Add documentation to all Coalton faux macros

[Izaakwltn]

Currently meta-dotting to certain Coalton macros drops you into a dead-end definition in /src/faux-macros.lisp with no documentation about implementation.

For instance and in Coalton only works on Booleans and can't be used for existence predicates like in Common Lisp.

This is a reasonable implementation but there is no documentation to confirm that this is the case.

These are the macros without documentation:

(define-coalton-editor-macro coalton:or (&rest args))

(define-coalton-editor-macro coalton:and (&rest args))

(define-coalton-editor-macro coalton:if (expr then else))

(define-coalton-editor-macro coalton:when (expr &body body))

(define-coalton-editor-macro coalton:unless (expr &body body))

(define-coalton-editor-macro coalton:cond (&rest clauses))

(define-coalton-editor-macro coalton:do (&body body))

(define-coalton-editor-macro coalton:return (&optional value))

(define-coalton-editor-macro coalton:loop (&body body))

(define-coalton-editor-macro coalton:while (test &body body))

(define-coalton-editor-macro coalton:while-let (pattern = test &body body))

(define-coalton-editor-macro coalton:for (pattern in iter &body body))

(define-coalton-editor-macro coalton:break (&optional label))

(define-coalton-editor-macro coalton:continue (&optional label))