RFR(s): 8073923: Files.lines() documentation needs clarification

[Stuart Marks]

Hi all,

Please review minor clarifications to Files.lines() and other Files methods that 
return streams. The changes emphasize that try-with-resources should be used. 
This also clarifies and strengthens a bit of the Stream class doc that talks 
about when to use try-with-resources on streams.

Bug:

        https://bugs.openjdk.java.net/browse/JDK-8073923

Webrev:

        http://cr.openjdk.java.net/~smarks/reviews/8073923/webrev.0/

Thanks,

s'marks