docs: add Twitter to supported providers

Author: tomasvotava

README.md

@@ -51,6 +51,7 @@ I tend to process Pull Requests faster when properly caffeinated 😉.
 - Github (credits to [Brandl](https://github.com/Brandl) for hint using `accept` header)
 - generic (see [docs](https://tomasvotava.github.io/fastapi-sso/reference/sso.generic/))
 - Notion
+- Twitter (X)
 
 ### Contributed