Update social links to include Mastodon

[menny]

• [ ] Official mastodon account: https://hachyderm.io/@anysoftkeyboard.
• [ ] Remove all Google Plus references
• [ ] Keep twitter? Or remove it?

[menny]

@AnXh3L0 can you take a look at this?

[menny]

@AnXh3L0 I think I added Mastodon correctly. Can you check?

[AnXh3L0]

Hi @menny, yes, you added it correctly.