Add chroma db docs

Author: NickBusey

docs/integrations/knowledge-base.md

@@ -51,4 +51,6 @@ Or you can comment directly on some lines of code in the PR. `@coderabbitai do n
 
 For self-hosted / on-premises deployments, you can enable the knowledge base features by setting `ON_PREM_KNOWLEDGE_BASE=true` in the environment variables for your self-hosted docker image.
 
-By default, CodeRabbit will store its data in the `coderabbitai/data` branch unless you set `ON_PREM_KNOWLEDGE_BASE_BRANCH=<branch_name>` with a different value.
+You must also be running ChromaDB. Use image `chromadb/chroma:0.5.20`. In your CodeRabbit docker image environment variables, set `CHROMADB_URL` to point to the hostname where ChromaDB can be reached. For persistance of your ChromaDB data, mount `/chroma/chroma` in the container to a volume mount. For more information on ChromaDB docker deployment, including how to set up authentication, refer to the [official documentation](https://docs.trychroma.com/deployment/docker). CodeRabbit will use CHROMA_CLIENT_AUTH_CREDENTIALS if it is set.
+
+By default, CodeRabbit will store its data in the `coderabbitai/data` branch unless you set `ON_PREM_KNOWLEDGE_BASE_BRANCH=<branch_name>` with a value.

docs/self-hosted/github.md

@@ -112,6 +112,8 @@ OAUTH2_CLIENT_SECRET=[<client-secret>]
 ON_PREM_KNOWLEDGE_BASE=[true]
 # The branch which CodeRabbit will store the knowledge base json files in.
 ON_PREM_KNOWLEDGE_BASE_BRANCH=[coderabbitai/data]
+# URL to the host running ChromaDB 0.5.20.
+CHROMADB_URL=[http://chromadb:8000]
 ```
 
 :::note