revert: fix(docs): set mode in file-local vars

emacs-straight/org-mode@e22b4eb7aa introduced a breaking change that
made it impossible to rely on .dir-locals.el to change org-mode buffers
in $EMACSDIR to doom-docs-org-mode (without infinite recursion), so we
used file-local variables in 7e400ab.

emacs-straight/org-mode@215de6176b reverted that change, so we can use
.dir-locals.el again, and this is my preference, since it requires less
boilerplate across our hundreds of org files.

Ref: emacs-straight/org-mode@215de6176b
Ref: emacs-straight/org-mode@e22b4eb7aa
Revert: 7e400abdc0

modules/lang/javascript/README.org

@@ -1,4 +1,3 @@
-# -*- mode: doom-docs-org -*-
 #+title:    :lang javascript
 #+subtitle: all(hope(abandon(ye(who(enter(here))))))
 #+created:  January 16, 2017