fixed slight error in a sentence

Author: Aaina26

content/en/docs/concepts/architecture/nodes.md

@@ -143,7 +143,7 @@ For example, you can set labels on an existing Node or mark it unschedulable.
 You can set optional node role(s) for nodes by adding one or more `node-role.kubernetes.io/<role>: <role>` labels to the node where characters of `<role>` 
 are limited by the [syntax](/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set) rules for labels.
 
-Kubernetes ignores the label value for node roles;by convention, you can set it to the same string you used for the node role in label key.
+Kubernetes ignores the label value for node roles; by convention, you can set it to the same string you used for the node role in the label key.
 
 You can use labels on Nodes in conjunction with node selectors on Pods to control
 scheduling. For example, you can constrain a Pod to only be eligible to run on