Add CC-BY to website footer

[gmmspi]

Add CC-BY to website footer and potentially outputs of the export tool

[chienleng]

added to footer and about page. it's linked to: https://creativecommons.org/licenses/by/4.0/

[chienleng]

Preview: https://feature-add-cc-by.opennem-fe-bl7.pages.dev/

[gmmspi]

This is great @chienleng

How hard would it be to also apply similar to exported charts? Say, in the bottom right of the export?

[chienleng]

Easy to add. Since it's exported and not interactive, should I just use the CC-BY logo or spell out the licence Licence: CC BY 4.0.

[gmmspi]

I think the logo would be good

[chienleng]