RFR: Joined the guide into a single file

[Andreas Lundblad]

On Wed, 7 Oct 2020 02:31:41 GMT, Jesper Wilhelmsson <jwilhelm at openjdk.org> wrote:

> I have left a forwarding pointer in the old files in case anyone has a link to the guide somewhere. Not sure if this is
> needed. Maybe it's better to just remove all the files directly?
> I did remove jbslabels.md since that file hasn't been published on the web server yet.
> 
> I didn't make any changes in the content except for removing references to getSource.md, hgHelp.md, and tClone.md since
> they are outdated and shouldn't be inlined in the guide. I also removed all TBD and sections with no content. Notes has
> been added in the todo list in README.md for all sections and TBDs that was removed.

I see a lot of deletions and few additions. Surely some content has been removed?

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PR: https://git.openjdk.java.net/guide/pull/28