Hide sensitive using pre defined regex patterns per major mode or buffer name.
It allows to define specific regex per each major mode or buffer name where we
want to hide sensitive data

Usage: For example if we want to add it to envrc files
  (require 'cloak-mode)
  (setq cloak-mode-patterns '((envrc-file-mode . "[a-zA-Z0-9_]+[ \t]*=[ \t]*\\(.*+\\)$")))
  (global-cloak-mode)

Or for a buffer by name:
  (require 'cloak-mode)
  (setq cloak-mode-patterns '(("*scratch*" . "[a-zA-Z0-9_]+[ \t]*=[ \t]*\\(.*+\\)$")))
  (global-cloak-mode)