docs: add groq to list of providers (#18503)

**Description:** Add Groq to the list of providers
**Issue:** None
**Dependencies:** None

docs/docs/integrations/platforms/index.mdx

@@ -16,6 +16,7 @@ These providers have standalone `langchain-{provider}` packages for improved ver
 - [Astra DB](/docs/integrations/providers/astradb)
 - [Exa Search](/docs/integrations/providers/exa_search)
 - [Google](/docs/integrations/platforms/google)
+- [Groq](/docs/integrations/providers/groq)
 - [IBM](/docs/integrations/providers/ibm)
 - [MistralAI](/docs/integrations/providers/mistralai)
 - [Nomic](/docs/integrations/providers/nomic)