In HA Cluster configuration, there is a common structure that allows multiple sets of key-value pairs. However, `pcs`, which is used by the `system_role_ha_cluster` for creating configuration, does support only a single set of the key-value pairs.

In the `system_role_ha_cluster` appeared two different approaches to deal with it:

• use only the first set and ignore the rest (in the most cases)
• merge multiple sets into one single set (in the case of `ha_cluster_node_options.attributes.attrs`)

Such inconsistency can confuse a user and may complicate the possible future addition of support for multiple sets. So, node attributes should be modified to behave like the other cases. Also in README should be the behavior explicitly mentioned.