RFR: JDK-8177910, Update zlib copyright note in idk/src/java.base/share/legal/zlib.md

[Xueming Shen]

Hi,

Please help review the copyright update change for

issue: https://bugs.openjdk.java.net/browse/JDK-8177910
webrev: http://cr.openjdk.java.net/~sherman/8177910/

Thanks!
Sherman