RFR: 8210: Update devguide to mention Protocol Rules for Eclipse 2023-06 onward [v2]

[Alex Macdonald]

> This PR adds some information to the devguide about using Eclipse 2023-06 and above. Newer Eclipse IDEs force the use of HTTPS for external update sites and artifacts, which out of the box conflicts with our local p2 repository.
> 
> The fix is to allow http in Preferences > Install/Update > Trust > Authorities > Protocol Rules. I've added a screenshot to doc as well highlighting where to find it. 
> 
> I had run into this yesterday when taking a look at some interesting behaviour I was seeing when testing the Jolokia PR https://github.com/openjdk/jmc/pull/548#issuecomment-1989331436.

Alex Macdonald has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:

 - Move the mention of the Preferences setting to be alongside the eclipse.ini method
 - 8210: Update devguide to mention Protocol Rules for Eclipse 2023-06 onward

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Changes: https://git.openjdk.org/jmc/pull/556/files
  Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=556&range=01
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jmc/pull/556.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/556/head:pull/556

PR: https://git.openjdk.org/jmc/pull/556