RFR: JDK-8306607: Apply 80-column output to javac supported version output

[Jonathan Gibbons]

Please review a trivial `noreg-doc` output to fix a "long lines" issue.
The solution should be good enough for at least a few years, and by then, we may have pruned the list of supported releases :-)

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

Commit messages:
 - JDK-8306607: Apply 80-column output to javac supported version output

Changes: https://git.openjdk.org/jdk/pull/13965/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13965&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306607
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/13965.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13965/head:pull/13965

PR: https://git.openjdk.org/jdk/pull/13965