mention -*- cookie for switching emacs modes and clarify file pattern text

### Autoloading \& Auto-recognition

For autoloading and auto-recognizing `in.*` and `*.lmp` files add the following

to `.emacs`:

To automatically turn on the LAMMPS mode for editing your input scripts,

use the following line as the **first** line of your script:

```

# -*- lammps -*-

```

For automatically switching on the LAMMPS mode based on filename patterns,

e.g. for `in.*` and `*.lmp` files, add the following code to your `.emacs`:

``` emacs-lisp

(autoload 'lammps-mode "lammps-mode.el" "LAMMPS mode." t)