Another minor diagnostics tweak.

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/logging/trunk@381887 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/logging/LogFactory.java

@@ -1105,7 +1105,8 @@ public abstract class LogFactory {
                             "Class '" + factoryClass + "' cannot be converted to '"
                             + LogFactory.class.getName() + "'."
                             + " Perhaps you have multiple copies of LogFactory in"
-                            + " the classpath?";
+                            + " the classpath? If so, consider using the"
+                            + " commons-logging-adapters.jar file.";
 
                         if (isDiagnosticsEnabled()) {
                             logDiagnostic(msg);