nit: s/#+BEGIN_SRC/#+begin_src, s/elisp/emacs-lisp/

From now on Doom will enforce two conventions for its org files for
consistency's sake:

- Lower-case meta-lines in org files, like #+begin_src, #+name, or
  #+end_quote (only exception are the top-level ones, like #+TITLE and
  #+STARTUP).
- Use 'emacs-lisp' as the lang specifier for elisp blocks rather than
  'elisp'. Emacs doesn't natively recognize the latter.

This will be reflected in our rewritten docs/*.org and module
README.org's.

modules/lang/org/config.el

@@ -17,7 +17,7 @@
   "An alist mapping languages to babel libraries. This is necessary for babel
 libraries (ob-*.el) that don't match the name of the language.
 
-For example, (fish . shell) will cause #+BEGIN_SRC fish blocks to load
+For example, (fish . shell) will cause #+begin_src fish blocks to load
 ob-shell.el when executed.")
 
 (defvar +org-babel-load-functions ()