RFR [9] 8133802: replace some tags (obsolete in html5) in security-libs docs

[Alexander Stepanov]

Hello,

Could you please review the following fix:
http://cr.openjdk.java.net/~avstepan/8133802/webrev.00
for
https://bugs.openjdk.java.net/browse/JDK-8133802
Just another portion of deprecated <tt> tags replaced with {@code } 
(some <xmp> tags were replaced as well).

Thanks,
Alexander