RFR - 8203614: Java API SSLEngine example code needs correction

[Jamil Nimeh]

Hello all,

This is a simple doc-only one-liner that fixes the sample code in 
SSLEngine to use the correct ByteBuffer in the capacity size check.

webrev: http://cr.openjdk.java.net/~jnimeh/reviews/8203614/webrev.01/
JBS: https://bugs.openjdk.java.net/browse/JDK-8203614

Thanks,
--Jamil