Install instructions for GN 4.0

[jhevenor]

Hi, I'm either very old or very new to GeoNetwork. It's been 10+ years since I last had a look. But I've been working with DGIWG metadata lately and found this plugin.

I've been attempting setup geonetwork from source on CentOS 8 following these instructions from the geonetwork download page, modified using this plugin's readme:

$ git clone --recursive git://github.com/geonetwork/core-geonetwork.git geonetwork
$ cd geonetwork
$ git checkout main
$ git submodule update --init

# schema plugins
cd schemas
git submodule add -b master https://github.com/metadata101/iso19139.dgiwg iso19139.dgiwg
cd ..

$ mvn clean install
$ cd web
$ mvn jetty-run

Two notes. First, the submodule add statement refers to a branch that doesn't exist. I only see that master exists here, so I used that.

Second, I get build errors related to 'could not find artifact'. I assume things have changes between 3 and 4, but I'm not familiar enough to get it working. I see some references to add-schema.sh in other plugins, but they reference 3.x as well, so I may be going about this the wrong way.

If there's a simple "change this to that" kind of answer I would appreciate it. Otherwise, I'm going to try again targeting GN 3.12 to see where that goes.

Thanks!