This commit changes the note in docs about required java version to note
the existence of the bundled jdk and how to bring your own java. It also
reorganizes the zip/targz docs as zip is no longer suitable on
Linux/MacOS.
This is a follow up to a previous change which set the error file path
for the package distributions. The observation here is that we always
set the working directory of Elasticsearch to the root of the
installation (i.e., Elasticsearch home). Therefore, we can specify the
error file path relative to this directory and default it to the logs
directory, similar to the package distributions.
