Hi roughrabbit,
You had all the pieces, just not in the correct order. <script> tags in HTML are evaluated in the order they appear in the source; and you had your <script> tags in exactly the opposite order.
The code to initialize Readmore, $('article').readmore({ speed: 80 });, has to come last because it depends on the code in readmore.js, which in turn depends on jQuery. So you'll see below, that I bring in jQuery, then Readmore, and then call $('article').readmore(...);.
Hope that helps,
Jed Foster