add `prog-asm.el' for assembly programming.

lisp/prog-asm.el

+;;; prog-asm.el --- Configuration for assembly code.
+;;; Commentary:
+
+;;; Code:
+(use-package nasm-mode
+  :ensure t
+  :mode "\\.nasm\\'")
+
+(provide 'prog-asm)
+;;; prog-asm.el ends here