node-executors-help: correct agent to node
This screen is in the nodes view and can be reached for:
/computer/(master)/configure
The help applies to all nodes (agents and master) and therefore this text
should say node.
<div>
The maximum number of concurrent builds that Jenkins may perform on this
- agent.
+ node.
<p>
A good value to start with would be the number of CPU cores on the machine.
Setting a higher value would cause each build to take longer, but could
