Create AGPL License

[elliotwutingfeng]

Addresses #235.

Recommending the AGPL license to ensure that source will be disclosed even when blahdns is distributed over a network; because the Alfis dependency is licensed under AGPLv3.

Feel free to choose any other license of your preference if the AGPL does not fit your needs.

[zoonderkins]

Actually BlahDNS is rely on

1. Dnsdist https://dnsdist.org/common/license.html (GNU v2)
2. Knot-resolver https://www.knot-resolver.cz/ (GPL)
3. Alfis https://github.com/Revertron/Alfis/blob/master/LICENSE (AGPL)
4. HAProxy https://www.haproxy.com/documentation/hapee/latest/licensing/ (GNU v2)
5. dns-over-https https://github.com/m13253/dns-over-https (MIT)

So I dont know what License to choose or should we actually need a License.
Another reason is BlahDNS is a personal self-hosted service. So which License should I use 😄

[elliotwutingfeng]

3. Alfis https://github.com/Revertron/Alfis/blob/master/LICENSE (AGPL)

Because of this dependency, you will need AGPLv3 specifically to comply with their requirements if you are disclosing the source code in public. If this were a private project where you do not disclose the source code and do not distribute the project at all, licensing is completely optional, but that's not the case here.

Permissions of this strongest copyleft license are conditioned on making available complete source code of licensed works and modifications, which include larger works using a licensed work, under the same license. Copyright and license notices must be preserved. Contributors provide an express grant of patent rights. When a modified version is used to provide a service over a network, the complete source code of the modified version must be made available.

[zoonderkins]

LGTM