RFR 8168677: Typo in API docs for com.sun.tools.attach

[harold seigel]

Hi,

Please review this trivial JDK-10 change to correct the spelling of 
"VirtalMachine" to "VirtualMachine".

Open Webrev: 
http://cr.openjdk.java.net/~hseigel/bug_8168677/webrev/index.html

JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8168677

Tested by running many jdk/ JTreg tests and by looking at the new doc pages.

Thanks, Harold