RFR: 8337276: jcmd man page update for PID in output filenames

[Kevin Walls]

Man page update for jcmd.

Add updates for the filename options/arguments affected by:
8334492: DiagnosticCommands (jcmd) should accept %p in output filenames and substitute PID

Also:
In the initial "command" summary, remove the text about "If the pid is 0.." as it is completely duplicated very shortly afterwards in the COMMANDS FOR JCMD section.

In Description:
Each diagnostic command has its own set of options and arguments .
 
Added "options and" because arguments and options are different and this can still be confusing.  Mentioning them as being different may help.

Similarly, added a short section describing that jcmds "may take options and arguments" and further spelling out that options are name=value and arguments are not, as this can still be confusing.

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Commit messages:
 - 8337276: jcmd man page update for PID in output filenames

Changes: https://git.openjdk.org/jdk/pull/20401/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20401&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8337276
  Stats: 36 lines in 1 file changed: 11 ins; 11 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/20401.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20401/head:pull/20401

PR: https://git.openjdk.org/jdk/pull/20401