Update braintrust.md

The Link to Braintrust was broken

Author: hassancs91

docs/integrations/braintrust.md

@@ -3,7 +3,7 @@ slug: /integrations/braintrust
 title: Braintrust
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-[Braintrust](braintrustdata.com) is an enterprise-grade stack for building AI products including: evaluations, prompt playground, dataset management, tracing, etc.
+[Braintrust](https://www.braintrustdata.com/) is an enterprise-grade stack for building AI products including: evaluations, prompt playground, dataset management, tracing, etc.
 
 Braintrust provides a Typescript and Python library to run and log evaluations and integrates well with Chroma.