Seems like you are trying distributed deployment of WSO2 Api Manager.
In the guide you mentioned its using same product binary for all four distributed components, but configuring them to use only required components accessed in each node.
And according to your question you need publisher and store run on one node together, and gateway and key manager to run on another node together. So what you have to do is following the documentation you mentioned carefully by doing both publisher/store changes in one node and both gateway/keymanager changes in other node.
Step 10 a-b points to WSO2REG_DB, which is created in Step 7 d. Before change the deployment, i would suggest to follow the document as it is, because it would help you to understand about the deployment.
You would need to have full configuration in 10 a & b, but since you have only one node, you have to have only one registry.xml with a sample configuration as follows,
<dbConfig name="govregistry">
<dataSource>jdbc/WSO2REG_DB</dataSource>
</dbConfig>
<remoteInstance url="https://store_publisher.apim-wso2.com">
<id>gov</id>
<dbConfig>govregistry</dbConfig>
<readOnly>false</readOnly>
<enableCache>true</enableCache>
<registryRoot>/</registryRoot>
</remoteInstance>
<mount path="/_system/governance" overwrite="true">
<instanceId>gov</instanceId>
<targetPath>/_system/governance</targetPath>
</mount>
Keep in mind to add the mapping to custom host name 'store_publisher.apim-wso2.com' used above to /etc/hosts file as follows,
xx.xxx.x.206 store_publisher.apim-wso2.com
which also explained in file as explained in 10-c.
Regards,
DarRay