[docs] Add version compatibility hint for logback

Issue alibaba#304

website/docs/maintenance/logging.md

@@ -56,6 +56,10 @@ For Fluss distributions this means you have to:
 * remove the `log4j-slf4j-impl` jar from the lib directory.
 * add the `logback-core`, and `logback-classic` jars to the lib directory.
 
+:::info
+Fluss currently uses SLF4J 1.7.x, which is _incompatible_ with logback 1.3.0 and higher.
+:::
+
 The Fluss distribution ships with the following logback configuration files in the conf directory, which are used automatically if logback is enabled:
 * `logback-console.xml`: used for CoordinatorServer/TabletServer if they are run in the foreground (e.g., Kubernetes).
 * `logback.xml`: used for CoordinatorServer/TabletServer by default.