Add configurable ingress, rename all files to .yaml for conformity.

charts/postiz/templates/postiz-config.yaml

@@ -0,0 +1,10 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ include "postiz.fullname" . }}-config
+  labels:
+    {{- include "postiz.labels" . | nindent 4 }}
+data:
+  {{- range $key, $value := .Values.env }}
+  {{ $key }}: {{ $value | quote }}
+  {{- end }}