Fix broken link in ODF-community PDF's and ODP's

[jimmysjolund]

The link to:

[Prioritizing by impact](https://developers.redhat.com/blog/2014/08/27/5-ux-tips-for-developers)—see grid in Máirín Duffy's "5 UX Tips for Developers"

needs to be updated in the different PDF and ODP documents. The markdown files are fixed.