[9] Review request for 8163501: NumberAxis: a couple of typos in the docs

[Vadim Pakhnushev]

Jonathan, Kevin,
Could you please review this fix?

https://bugs.openjdk.java.net/browse/JDK-8163501
http://cr.openjdk.java.net/~vadim/8163501/webrev.00/

Thanks,
Vadim