RFR: JDK-8300042: Improve CPU related JFR events descriptions [v2]

[Matthias Baesken]

> There are a number of JFR events dealing with CPU related information. Those sometimes miss descriptions or have very limited descriptions, this can be improved.

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  Adjust CPULoad description

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11969/files
  - new: https://git.openjdk.org/jdk/pull/11969/files/0956a182..9d8c701c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11969&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11969&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/11969.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11969/head:pull/11969

PR: https://git.openjdk.org/jdk/pull/11969