Update USERS.md (#538)

Signed-off-by: Stan van Rooy <[email protected]>

Author: stanvanrooy

USERS.md

@@ -8,3 +8,4 @@ If you're using Parseable in your organization, please try to add your company n
 | ------------ | ------- | ------------------ |
 | [HireXL](https://www.hirexl.in/) | [@A4abs](https://github.com/A4abs) | Frontend application logging |
 | [ChistaDATA](https://chistadata.io/) | [Adheip Singh](mailto:[email protected]) | Centralized Kubernetes Logging |
+| [Elfsquad](https://elfsquad.io) | [Stan van Rooy](https://github.com/stanvanrooy) | Centralized application/infrastructure logging |