fix error in AliasableEvalFunc documentation
fix error in AliasableEvalFunc documentation

shaohua-zhang/incubator-datafu,apache/incubator-datafu,apache/incubator-datafu,shaohua-zhang/incubator-datafu,apache/incubator-datafu,shaohua-zhang/incubator-datafu,shaohua-zhang/incubator-datafu,shaohua-zhang/incubator-datafu,apache/incubator-datafu,apache/incubator-datafu