RFR 8160036: Java API doc for method minusMonths in LocalDateTime class needs correction

[Bhanu Gopularam]

Hi all,

Could you please review fix for following issue?

Bug id: https://bugs.openjdk.java.net/browse/JDK-8160036

Solution: Corrected documentation for couple of methods in LocalDateTime and 
OffsetDateTime classes

Webrev: http://cr.openjdk.java.net/~bgopularam/8160036/webrev.00

Thanks,
Bhanu