Change type in values.yaml comment

[timofey-drozhzhin]

The values.yaml comment in opentelemetry-collector and opentelemetry-kube-stack charts improperly refer to k8sobjects receiver in singular form.

Current snippet (Bad)

# Adds the k8sobject receiver to the logs pipeline

Proposed snippet (Good)

# Adds the k8sobjects receiver to the logs pipeline

Since the receiver is called k8sobjects, it will be proper to call it that. Referring it in singular form, causes users like myself to add k8sobject (singular form) to config.service.pipelines.logs.receivers, resulting in errors.

[timofey-drozhzhin]

I added a commit here #1451