gnu: emacs-elisp-demos: Improve package style.

* gnu/packages/emacs-xyz.scm (emacs-elisp-demos)[arguments]: Use
G-expressions.
<#:include>: Use default include.

Change-Id: I44960fa1d7ddec2d15e6927aa76eafb32a03e627

gnu/packages/emacs-xyz.scm

@@ -8731,9 +8731,10 @@ files which are intended to be packages.")
          "1pgg5z3z2pf0vps86lrkxfr36v4c24mpgvj551gixdlrm2s55p0l"))))
     (build-system emacs-build-system)
     (arguments
-     `(#:include '("\\.el$" "\\.org$")
-       #:tests? #t
-       #:test-command '("make" "test")))
+     (list
+      #:include #~(cons* "\\.org$" %default-include)
+      #:tests? #t
+      #:test-command #~(list "make" "test")))
     (home-page "https://github.com/xuchunyang/elisp-demos/")
     (synopsis "Enhance @code{*Help*} buffers with additional examples")
     (description