Add Reactor && Mutiny to advanced topics (#3355)

* feat: add Mutiny support

* Update gatsby-config.js

* doc: Add Reactor && Mutiny to advanced topics

Co-authored-by: Martin Bonnin <martin@mbonnin.net>

README.md

@@ -38,7 +38,7 @@ If you'd like to add Apollo Android to an existing project:
 
 ## Advanced topics
 
-Check [the project website](https://www.apollographql.com/docs/android/) for in depth documentation about [caching](https://www.apollographql.com/docs/android/essentials/caching/), [plugin configuration](https://www.apollographql.com/docs/android/essentials/plugin-configuration/), [android](https://www.apollographql.com/docs/android/advanced/android/), [file upload](https://www.apollographql.com/docs/android/advanced/file-upload/), [coroutines](https://www.apollographql.com/docs/android/advanced/coroutines/), [rxjava2](https://www.apollographql.com/docs/android/advanced/rxjava2/), [rxjava3](https://www.apollographql.com/docs/android/advanced/rxjava3/), [persisted queries](https://www.apollographql.com/docs/android/advanced/persisted-queries/), [no runtime](https://www.apollographql.com/docs/android/advanced/no-runtime/), [migrations](https://www.apollographql.com/docs/android/essentials/migration/) and much more...
+Check [the project website](https://www.apollographql.com/docs/android/) for in depth documentation about [caching](https://www.apollographql.com/docs/android/essentials/caching/), [plugin configuration](https://www.apollographql.com/docs/android/essentials/plugin-configuration/), [android](https://www.apollographql.com/docs/android/advanced/android/), [file upload](https://www.apollographql.com/docs/android/advanced/file-upload/), [coroutines](https://www.apollographql.com/docs/android/advanced/coroutines/), [rxjava2](https://www.apollographql.com/docs/android/advanced/rxjava2/), [rxjava3](https://www.apollographql.com/docs/android/advanced/rxjava3/), [reactor](https://www.apollographql.com/docs/android/advanced/reactor/), [mutiny](https://www.apollographql.com/docs/android/advanced/mutiny/), [persisted queries](https://www.apollographql.com/docs/android/advanced/persisted-queries/), [no runtime](https://www.apollographql.com/docs/android/advanced/no-runtime/), [migrations](https://www.apollographql.com/docs/android/essentials/migration/) and much more...
 
 ## IntelliJ Plugin