Add workers settings to configuration manual

changelog.d/14086.doc

@@ -0,0 +1 @@
+Add workers settings to [configuration manual](https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html#individual-worker-configuration).

docs/sample_log_config.yaml

@@ -6,7 +6,7 @@
 # Synapse also supports structured logging for machine readable logs which can
 # be ingested by ELK stacks. See [2] for details.
 #
-# [1]: https://docs.python.org/3.7/library/logging.config.html#configuration-dictionary-schema
+# [1]: https://docs.python.org/3/library/logging.config.html#configuration-dictionary-schema
 # [2]: https://matrix-org.github.io/synapse/latest/structured_logging.html
 
 version: 1