Grammar fix (#4801)

Signed-off-by: Mischa Gresser <mgresser@dstillery.com>

docs/chart_best_practices/labels.md

@@ -28,7 +28,7 @@ Name|Status|Description
 `app.kubernetes.io/name` | REC | This should be the app name, reflecting the entire app. Usually `{{ template "name" . }}` is used for this. This is used by many Kubernetes manifests, and is not Helm-specific.
 `helm.sh/chart` | REC | This should be the chart name and version: `{{ .Chart.Name }}-{{ .Chart.Version \| replace "+" "_" }}`.
 `app.kubernetes.io/managed-by` | REC | This should always be set to `{{ .Release.Service }}`. It is for finding all things managed by Tiller.
-`app.kubernetes.io/instance` | REC | This should be the `{{ .Release.Name }}`. It aid in differentiating between different instances of the same application.
+`app.kubernetes.io/instance` | REC | This should be the `{{ .Release.Name }}`. It aids in differentiating between different instances of the same application.
 `app.kubernetes.io/version` | OPT | The version of the app and can be set to `{{ .Chart.AppVersion }}`.
 `app.kubernetes.io/component` | OPT | This is a common label for marking the different roles that pieces may play in an application. For example, `app.kubernetes.io/component: frontend`.
 `app.kubernetes.io/part-of` | OPT | When multiple charts or pieces of software are used together to make one application. For example, application software and a database to produce a website. This can be set to the top level application being supported.