Improve http service and update Readme (#167)

This PR adds some options for the http service:

- loadBalancerIP
- nodePort
- externalTrafficPolicy
- externalIPs

Also updated the README and values.yml with the values.

Added storageClass explanation in README and empty value in values.yml

Fixes: #162

Co-authored-by: Lucas Hahn <lucas.hahn@novum-rgi.de>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/167
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-by: 6543 <6543@obermui.de>
Co-authored-by: luhahn <luhahn@noreply.gitea.io>
Co-committed-by: luhahn <luhahn@noreply.gitea.io>

templates/gitea/http-svc.yaml

@@ -11,6 +11,19 @@ spec:
   {{- if and .Values.service.http.loadBalancerIP (eq .Values.service.http.type "LoadBalancer") }}
   loadBalancerIP: {{ .Values.service.http.loadBalancerIP  }}
   {{- end }}
+  {{- if .Values.service.http.loadBalancerSourceRanges }}
+  loadBalancerSourceRanges:
+  {{- range .Values.service.http.loadBalancerSourceRanges }}
+    - {{ . }}
+  {{- end }}
+  {{- end }}
+  {{- if .Values.service.http.externalIPs }}
+  externalIPs:
+    {{- toYaml .Values.service.http.externalIPs | nindent 4 }}
+  {{- end }}
+  {{- if .Values.service.http.externalTrafficPolicy }}
+  externalTrafficPolicy: {{ .Values.service.http.externalTrafficPolicy }}
+  {{- end }}
   {{- if and .Values.service.http.clusterIP (eq .Values.service.http.type "ClusterIP") }}
   clusterIP: {{ .Values.service.http.clusterIP }}
   {{- end }}