Update `License.html`

[delphidabbler]

There is a broken link to https://www.aha-soft.com/ in the Required Notices section of License.html that needs marking as such.

Also change the URL required for acknowledgement of the CodeSnip image set from GitHub to delphidabbler.com.

Check the license for any further necessary changes.

[delphidabbler]

Implemented at issue 1e78995

[delphidabbler]

Included in release 4.21.0