Update links to documentation in sample config (#10287)

changelog.d/10287.doc

docs/sample_config.yaml

docs/sample_log_config.yaml

synapse/config/consent.py

synapse/config/database.py

synapse/config/jwt.py

synapse/config/logger.py

synapse/config/modules.py

synapse/config/oidc.py

synapse/config/password_auth_providers.py

synapse/config/repository.py

synapse/config/server.py

synapse/config/spam_checker.py

synapse/config/stats.py

synapse/config/tracer.py

synapse/config/user_directory.py