RFR [9] 8133459: replace <tt> tags (obsolete in html5) in java.nio docs

[Alexander Stepanov]

Hello,

Could you please review the following fix:
http://cr.openjdk.java.net/~avstepan/8133459/webrev.00/index.html
for
https://bugs.openjdk.java.net/browse/JDK-8133459

Just a next portion of deprecated '<tt>' tags replaced (didn't touch all 
these multiple ' 's to avoid undesirable formatting changes).

specdiff did not detect any changes in java.nio.*

Regards,
Alexander