Docs: conflicting information about how they are licensed

[Jane Sandberg]

Steps to recreate:

1) Go to a licensing page within one of the official Evergreen manuals (e.g., http://docs.evergreen-ils.org/reorg/3.2/acquisitions/licensing.html)

2) Note that the text says "This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License."

3) Scroll down to the bottom and find the creative commons icon. Click on it.

4) Note that this links to the Create Commons Attribution-ShareAlike 4.0 International License instead.

We should make these consistent.