Add comments and availability

Author: benjie

src/pages/blog/2025-06-19-multioption-inputs-with-oneof/index.mdx

@@ -99,6 +99,42 @@ input GalleryInput {
   including Ruby, Java, JavaScript and .NET already ship `@oneOf` as a stable
   feature
 
+You might wonder why this is expressed as a directive in SDL rather than
+explicitly having a new type keyword; Brad Baker, contributor to GraphQL-Java,
+summed it up in [this comment back in
+2023](https://github.com/graphql/graphql-spec/pull/825#issuecomment-1659900665):
+
+> use of the directive means that:
+>
+> - it's minimally invasive in terms of SDL tooling that might be out there,
+> - it's minimally invasive in terms of Introspection,
+> - it's minimally invasive in terms of engine implementation, it proved quite easy to implement in graphql-java.
+>
+> Great stuff!
+
+Since then there have been a number of reports of success:
+
+> I'm very happy with where this landed. We'd use it internally at my company. -- [Ethan Resnick](https://github.com/graphql/graphql-spec/pull/825#issuecomment-2128262620)
+
+> More positive feedback: We are using it at HubSpot through the graphql-java implementation and look forward to it becoming standardized. -- [Henry Q. Dineen](https://github.com/graphql/graphql-spec/pull/825#issuecomment-2128324080)
+
+> I implemented support for OneOf input objects for the Caliban GraphQL library (Scala) [...] it's been fairly straightforward implementing support for it and I couldn't really identify any areas that could have been improved. -- [kyri-petrou](https://github.com/kyri-petrou)
+
+> We have been eagerly waiting at Jobber for this to land as well. [...] We have many use cases internally for it and we're very excited to see this land! -- [Clinton Pahl](https://github.com/graphql/graphql-spec/pull/825#issuecomment-2135724148)
+
+> Colleagues at work (Atlassian) have been really happy with @oneOf, works exactly as you want it to and I haven't heard any negative feedback. -- [Donna Zhou](https://github.com/dondonz)
+
+## Availability
+
+`@oneOf` is already available in the following implementations of GraphQL:
+
+- GraphQL.js v16+
+- GraphQL Ruby v2.0.21+
+- GraphQL.NET v8+
+- GraphQL Java v21.2+
+- HotChocolate v16.0.0+
+- Probably others!
+
 ## The bottom line
 
 `@oneOf` allows for more expressive, capable, and less overwhelming schemas,