2.9 release notes: Add warning about download commands

Add a warning that reminds administrators that the download-commands
plugin must be installed for getting download-commands on the new
change screen. This warning was already included in the 2.8 release
notes but it makes sense to add this information to the 2.9 release
notes as well. Some people may not have been interested in the beta
version of the new change screen in 2.8 and hence they may have
ignored the need for installing the download commands plugin.

In addition provide more detailed instructions about how the
download-commands plugin can be installed.

Also add a warning about upgrading the plugin, since the 2.8 version
of the download-commands plugin doesn't work with Gerrit 2.9. Explain
that interactive init must be used to upgrade the plugin.

Change-Id: I2101e0a3974ddb8d1fdf198941edc99305351650
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
1 file changed