I've also enabled Facebook and Twitter logins as well, I believe!
Note that if your social media accounts share the same email address, you can sign in with them interchangeably (and with an account you've manually signed up for as well, of course). So if you signed up for our forum as
firstname.lastname@example.org, and your Facebook or Twitter or Github accounts are also using
email@example.com as the email address, then you can sign in with any of them and you'll be logged into the same account.
However, if your social media accounts use different email addresses (say, you sign in to Facebook as
firstname.lastname@example.org and Github as
email@example.com) then if you use both to sign in here, you'll get two separate forum accounts, and we can't merge them (this is a Discourse limitation). So if you want to start using social login to sign in here to your already existing account, then be sure that they have the same email addresses set.
As Jono says, let us know if there are any problems!