RFR: 8252584: HotSpot Style Guide should permit alignas

[Julian Waters]

Add alignas to the permitted features set. Though the corresponding entry mentions this should not be done for classes, there's no actual difference in practice with all our supported compilers, because their nonstandard syntax also has the same limitations and issues with dynamic allocation as the C++ alignas, and including such a restriction of falling back to ATTRIBUTE_ALIGNED in the case of classes in the style guide would ultimately not really serve much of a point

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

Commit messages:
 - Include the correct pandoc emitted html files
 - Restore html files
 - HotSpot Style Guide

Changes: https://git.openjdk.org/jdk/pull/11315/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11315&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8252584
  Stats: 5 lines in 2 files changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11315.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11315/head:pull/11315

PR: https://git.openjdk.org/jdk/pull/11315