remove mention of self-hosted knowledge base

Author: harjotgill

docs/self-hosted/github.md

@@ -123,7 +123,6 @@ OAUTH2_CLIENT_SECRET=[<client-secret>]
 - For `GITHUB_APP_PEM_FILE`, flatten the PEM file by replacing newlines with `\n`.
 - For `GITHUB_HOSTNAME`, use GitHub Enterprise server's hostname, for example, “github.acme-inc.com”
 - You can generate `CODERABBIT_API_KEY` from CodeRabbit UI -> Organizations Settings -> API Keys.
-- Refer to the [Self-hosted knowledge base](/integrations/knowledge-base#self-hosted) section for details on the `ON_PREM_KNOWLEDGE_BASE`.
 
 :::