RFR: 8348180: Remove mention of include of precompiled.hpp from the HotSpot Style Guide [v2]

[Stefan Karlsson]

> [JDK-8347909](https://bugs.openjdk.org/browse/JDK-8347909) removed the need for HotSpot devs to include the precompiled.hpp. This is the PR to reflect that.
> 
> I know that there is some process around updating the style guide, but I can't find it, so I'm starting with a plain PR.

Stefan Karlsson has updated the pull request incrementally with two additional commits since the last revision:

 - Update hotspot-style.md
 - Update hotspot-style.html

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23210/files
  - new: https://git.openjdk.org/jdk/pull/23210/files/09c88c4f..9cfbc1dc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23210&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23210&range=00-01

  Stats: 8 lines in 2 files changed: 4 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/23210.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23210/head:pull/23210

PR: https://git.openjdk.org/jdk/pull/23210