Adding hiop as known user (apache#18114)

## Which issue does this PR close?

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- Doesn't close an issue.

## Rationale for this change

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Hi we are hiop, a Serverless Data Logistic Platform.
We use DataFusion as a core part of our backend engine, and it plays a
crucial role in our data infrastructure. Our team members are passionate
about the project and actively try contribute to its development
(@dariocurr).

We’d love to have Hiop listed among the Known Users to show our support
and help the DataFusion community continue to grow.

## What changes are included in this PR?

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Just adding hiop as known user

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## Are there any user-facing changes?

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Author: enryls

docs/source/user-guide/introduction.md

@@ -109,6 +109,7 @@ Here are some active projects using DataFusion:
 - [Funnel](https://funnel.io/) Data Platform powering Marketing Intelligence applications.
 - [GlareDB](https://github.com/GlareDB/glaredb) Fast SQL database for querying and analyzing distributed data.
 - [GreptimeDB] Open Source & Cloud Native Distributed Time Series Database
+- [hiop](https://hiop.io) Serverless Data Logistic Platform
 - [HoraeDB] Distributed Time-Series Database
 - [Iceberg-rust](https://github.com/apache/iceberg-rust) Rust implementation of Apache Iceberg
 - [InfluxDB] Time Series Database