Enable custom namespace deployment

[diecgia]

Hi,
Currently, the chart does not allow deployment to a custom namespace. In the templates, it's set as follows:
namespace: {{ .Release.Namespace }}

Could we enable an option to set a custom namespace in the templates, similar to the following:

{{- define "k8s-monitoring.namespace" -}}
{{- if .Values.namespaceOverride -}}
{{- .Values.namespaceOverride -}}
{{- else -}}
{{- .Release.Namespace -}}
{{- end -}}
{{- end -}}

And set it in the values file like this:
namespaceOverride: custom-namespace

This would be useful when we use it as a subchart of our custom chart, allowing us to install it in a custom namespace separate from other subcharts.