Enhance documentation for adding namespaces

I've seen this asked in Discord a lot of times and there is even a stack overflow post about it https://stackoverflow.com/questions/76323318/does-anyone-have-an-idea-on-how-to-create-namespaces-in-hyperledger-firefly

Adding a new namespace to the config is not straight forward based on the "reference" and "configuration" sections in the documentation. It will be great to have a tutorial to add a new namespace, especially if this is based on the new Helm Charts!