Update CHANGELOG.md to inform Sep-24 Protocol Version

[reecexlm]

What

I am proposing this change to the java-stellar-anchor-sdk in order to make it possible for partners and service providers to inform their clients about which sep-24 protocol version they currently support. The change supports the following questions from our partner:

1. Each time there is a change, v. 1.0.13, 1.1.0, 2.6.0, etc. can we see what versions have been release and the dates?
2. Stellar would provide documentation of the change. Someone at (partner) would need to determine if we need to build to the latest version?

with this change, we will provide a statement about protocol support in the change log of the SDK.

this is only a change to the changelog. will update the changelog with statement of protocol support each release.

Why

to inform service providers and sep-24 clients about what protocol support the SDK they or their service provider is using supports.

Known limitations

still requires manual communication. we are planning to look into if this is something that can be facilitated via information within the sep24 /info endpoint itself.

[stellar-jenkins]

Something went wrong with PR preview build please check

[Ifropc]

We don't maintain core legacy, except critical patches. Closing the PR