RFR: Add missing JFR mailinglist [v2]

[Yang Yi]

> Hi, I found that the code owner section of the latest version is missing jfr-related content, this PR will amend this content.

Yang Yi has updated the pull request incrementally with one additional commit since the last revision:

  just reserve JFR

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

Changes:
  - all: https://git.openjdk.java.net/guide/pull/44/files
  - new: https://git.openjdk.java.net/guide/pull/44/files/e6e56e95..fc043189

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=guide&pr=44&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=guide&pr=44&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/guide/pull/44.diff
  Fetch: git fetch https://git.openjdk.java.net/guide pull/44/head:pull/44

PR: https://git.openjdk.java.net/guide/pull/44