Allow string-set bootnodes to still work

Signed-off-by: Edward Evans <edward.evans@consensys.net>

templates/config.toml.j2

@@ -94,13 +94,18 @@ permissions-nodes-contract-address="{{ besu_permissions_nodes_contract_address }
 {% endif %}
 
 {% if besu_bootnodes|length > 0 %}
+{% if besu_bootnodes is string %}
+# bootnodes
+bootnodes={{besu_bootnodes}}
+{% else %}
 # bootnodes
 bootnodes=[{{besu_bootnodes|map('to_json')|join(',')}}]
 {% endif %}
+{% endif %}
 
 {% if orion_version is defined %}
 # Orion
 privacy-enabled=true
 privacy-url="http://127.0.0.1:8888"
 privacy-public-key-file="{{ orion_config_dir }}/{{ orion_key_name }}.pub"
-{% endif %}
+{% endif %}