fix: remove go:generate directive for configdocsgen (#852)

The docs moved from docs/pages/references/configuration.mdx to
docs/content/self-hosting/configuration.mdoc, so the go:generate
directive points at a nonexistent path and breaks goreleaser
(`go generate ./...` in before hooks). The Makefile target
`make docs/generate/config` is preserved for manual use.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: alexluong

internal/config/config.go

@@ -1,4 +1,3 @@
-//go:generate go run ../../cmd/configdocsgen/main.go -input-dir . -output-file ../../docs/pages/references/configuration.mdx
 package config
 
 import (