fix: update Slack channel link in contribution guidelines

Author: xuafeng

README.md

@@ -88,7 +88,7 @@ You can find more detailed usage guides in the CLI [README.md](cli/README.md).
 
 ## Contribute to Benchmarks
 
-We welcome community contributions to enrich existing benchmarks (e.g., by adding more exam problems to the System Exam benchmark and more system artifacts to System Artifact and System Modeling benchmark), port your existing benchmarks, and more importantly to create new system intelligence benchmarks with our framework. See below for detailed instructions. We believe that such collective community efforts will advance AI to its next level and help realize System Intelligence, unlocking the potential of AI-driven computing system innovations. If you are interested in contributing or already have good system benchmarks, please let us know. We have set up a [slack channel](sys-intelligence.slack.com) at sys-intelligence.slack.com.
+We welcome community contributions to enrich existing benchmarks (e.g., by adding more exam problems to the System Exam benchmark and more system artifacts to System Artifact and System Modeling benchmark), port your existing benchmarks, and more importantly to create new system intelligence benchmarks with our framework. See below for detailed instructions. We believe that such collective community efforts will advance AI to its next level and help realize System Intelligence, unlocking the potential of AI-driven computing system innovations. If you are interested in contributing or already have good system benchmarks, please let us know. We have set up a [slack channel](https://join.slack.com/t/sys-intelligence/shared_invite/zt-3hpkgr2aa-NnuPxUbyHr45S89DFi_N1A) at sys-intelligence.slack.com.
 
 > [!NOTE] 
 > We suggest getting starting by walking through the basic concept of a AI benchmark: [Benchmark Abstraction](doc/benchmark_abstract.md). After understanding the basic concept, you can decide whether to Contribute to Existing Benchmarks, Porting Existing Benchmarks, or  Creating New Benchmarks.