License updated to Creative Commons

Hello everyone! I hope you've been enjoying Lyric's Ledger of Legends, and that our work has inspired a new character or two. With the news of the 5.1 SRD being released under the Creative Commons license, we decided it would be prudent to switch over to using that instead of the OGL! The last page has been changed to use the new license and include a changelog, in case we make future adjustments, though that's the only difference for now. If you have any further suggestions for changes or other feedback, do let us know!

- Ashley