Added documentation for node repurpose tool and included documentation on how to repurpose nodes safely. Adjusted order of tools in `elasticsearch-node` tool since the repurpose tool is most likely to be used.
Co-Authored-By: David Turner <david.turner@elastic.co>
This commit, mostly authored by @DaveCTurner,
adds documentation for elasticsearch-node tool #37696.
(cherry picked from commit 09425d5a5158c2d3fdad794411b3bbc4bba47b15)