Add Unity to provisional account providers (discord#7512)

We added support Unity as a provider for provisional accounts, this adds them to the bulleted list

Author: swilliams

docs/discord-social-sdk/development-guides/using-provisional-accounts.mdx

@@ -78,6 +78,7 @@ We currently support the following provider types:
 - OpenID Connect (OIDC)
 - Steam Session Tickets
 - Epic Online Services (EOS)
+- Unity
 
 ---
 
@@ -420,4 +421,4 @@ Now that you've set up provisional accounts for your game, you can explore more
 [`Client::GetTokenFromDeviceProvisionalMerge`]: https://discord.com/developers/docs/social-sdk/classdiscordpp_1_1Client.html#afd2207590ae7d6f60ee7bbb4fc7c21c8
 [`Client::GetTokenFromProvisionalMerge`]: https://discord.com/developers/docs/social-sdk/classdiscordpp_1_1Client.html#a41062b7dafa331ddd2320daf1b4b273b
 [`Client::SetTokenExpirationCallback`]: https://discord.com/developers/docs/social-sdk/classdiscordpp_1_1Client.html#aab5bfc76809ea22e79f2f7a067ac4519
-[`Client::UpdateProvisionalAccountDisplayName`]: https://discord.com/developers/docs/social-sdk/classdiscordpp_1_1Client.html#a7485979ab2d4c533b75f8efd5e50bc60
+[`Client::UpdateProvisionalAccountDisplayName`]: https://discord.com/developers/docs/social-sdk/classdiscordpp_1_1Client.html#a7485979ab2d4c533b75f8efd5e50bc60