[9.3 doc fix] clarification of Solaris versions

Hello,

One of my colleagues, who is relatively new to PostgreSQL, asked me if
PostgreSQL supports Solaris 11.  The reason why he had this question is that
the following page says "Solaris 10" instead of "Solaris 10 and later".

http://www.postgresql.org/docs/devel/static/kernel-resources.html

So, I suggest this tiny modification to avoid misunderstanding.  In
addition, I suggest removing references to OpenSolaris because OpenSolaris
is already discontinued.

I'm attaching one patch file.  Could you commit this change?

Regards
MauMau