Tweaked the README to cover configuring the collection name using Log4J pattern.

spring-data-mongodb-log4j/README.md

@@ -11,21 +11,21 @@ To use it, configure a host, port, (optionally) applicationId, and database prop
     log4j.appender.stdout.host = localhost
     log4j.appender.stdout.port = 27017
     log4j.appender.stdout.database = logs
+    log4j.appender.stdout.collectionPattern = %c
     log4j.appender.stdout.applicationId = my.application
     log4j.appender.stdout.warnOrHigherWriteConcern = FSYNC_SAFE
 
 It will even support properties in your MDC (so long as they're Strings or support .toString()).
 
 The collection name is configurable as well. If you don't specify anything, it will use the Category name.
-If you want to specify a collection name, you can give it a String.format() string which will be passed the
+If you want to specify a collection name, you can give it a Log4J pattern layout format string which will have
-following parameters:
+the following additional MDC variables in the context when the collection name is rendered:
-
+
-1. Calendar.YEAR
+    "year" = Calendar.YEAR
-2. Calendar.MONTH
+    "month" = Calendar.MONTH + 1
-3. Calendar.DAY_OF_MONTH
+    "day" = Calendar.DAY_OF_MONTH
-4. Calendar.HOUR_OF_DAY
+    "hour" = Calendar.HOUR_OF_DAY
-5. event.getLevel().toString()
+    "applicationId" = configured applicationId
-6. event.getLogger().getName()
 
 An example log entry might look like: