Update comments

Author: shunping

runners/spark/3/build.gradle

@@ -62,15 +62,16 @@ sparkVersions.each { kv ->
     // no longer available in SLF4J 2.x.  This results in a
     // `java.lang.NoClassDefFoundError`.
     //
-    // The workaround here provides an SLF4J 1.x binding to resolve the error.
-    // Only `org.apache.logging.log4j:log4j-slf4j-impl` provides a compatible
-    // SLF4J 1.x binding regardless SLF4J upgrade.
-    // Other package from SLF4J (e.g., slf4j-simple, slf4j-reload4j) are
-    // unsuitable because they also get upgraded as new SLF4J version is in use,
-    // and the binding classes are no longer in there.
+    // The workaround is to provide an SLF4J 1.x binding module out of group
+    // `org.slf4j` to resolve the issue.
+    // Module `org.apache.logging.log4j:log4j-slf4j-impl` is an example that
+    // provides a compatible SLF4J 1.x binding regardless SLF4J upgrade.
+    // Binding/provider modules under group `org.slf4j` (e.g.,
+    // slf4j-simple, slf4j-reload4j) get upgraded as a new SLF4J version is in
+    // use, and therefore do not contain the 1.x binding classes.
     //
     // Notice that Spark 3.1.x uses `ch.qos.logback:logback-classic` and is
-    // unaffected by this SLF4J upgrade. Spark 3.3.x already uses
+    // unaffected by the SLF4J upgrade. Spark 3.3.x already uses
     // `log4j-slf4j-impl` so it is also unaffected.
     if ("$kv.key" >= "320" && "$kv.key" <= "324") {
       "sparkVersion$kv.key" library.java.log4j2_slf4j_impl