RFR: JDK-8276239: Better tables in java.util.random package summary

[Ludvig Janiuk]

The tables are now striped, and they use row headers (which is a nice-to-have for accessibility).

-------------

Commit messages:
 - Striped tables and table row headers

Changes: https://git.openjdk.java.net/jdk/pull/6196/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6196&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8276239
  Stats: 32 lines in 1 file changed: 0 ins; 0 del; 32 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6196.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6196/head:pull/6196

PR: https://git.openjdk.java.net/jdk/pull/6196