RFR: 8319948: jcmd man page needs to be updated [v2]

[David Holmes]

> Please review these missing updates to the `jcmd` manpage - see JBS issue for details.
> 
> I also fixed the sub-command ordering in a few places and a couple of minor formatting fixes.
> 
> Thanks to @tstuefe for collating the initial information on what was missing. I used to `jcmd help <cmd>` option to compare the help text with the manpage text and adjusted the manpage accordingly (and found a few more omissions - some of which will be fixed by follow up RFE by the respective owners).

David Holmes has updated the pull request incrementally with one additional commit since the last revision:

  Fix two formatting errors and make VM.flags consistent with help text

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17213/files
  - new: https://git.openjdk.org/jdk/pull/17213/files/9e47816e..c410c17f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17213&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17213&range=00-01

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/17213.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17213/head:pull/17213

PR: https://git.openjdk.org/jdk/pull/17213