Update artifact_catalog.dox

add space to TSK_VALUE line and added TSK_COMMENT as an optional attribute to the TSK_RECENT_OBJECT artifact.

bindings/java/doxygen/artifact_catalog.dox

@@ -529,7 +529,8 @@ Indicates recently accessed content. Examples: Recent Documents or Recent Downlo
 - TSK_PROG_NAME (Application or application extractor that stored this object as recent)
 - TSK_DATETIME (A timestamp associated with the content, in seconds since 1970-01-01T00:00:00Z. Ex: creation time)
 - TSK_NAME (If found in the registry, the name of the attribute)
-- TSK_VALUE(If found in the registry, the value of the attribute)
+- TSK_VALUE (If found in the registry, the value of the attribute)
+- TSK_COMMENT (What the source of the attribute may be)