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>

values.yaml

@@ -33,6 +33,9 @@ service:
     clusterIP: None
     #loadBalancerIP:
     #nodePort:
+    #externalTrafficPolicy:
+    #externalIPs:
+    loadBalancerSourceRanges: []
     annotations:
   ssh:
     type: ClusterIP
@@ -95,6 +98,7 @@ persistence:
     - ReadWriteOnce
   labels: {}
   annotations: {}
+  # storageClass:
 
 # additional volumes to add to the Gitea statefulset.
 extraVolumes: