vcs: add type declaration for *vcs-projects-roots*
vcs: add type declaration for *vcs-projects-roots*

Loading the init file also throws the type error:

The value
  ("~/projets" "~/work" ("~/bacasable/lisp-projects") "~/common-lisp"
   "~/quicklisp/local-projects")

is not of type
  (SATISFIES NEXT::LIST-OF-STRINGS-P)

jmercouris/NeXT,jmercouris/NeXT