NIT-938 Instuctions added on how to modify and publish a chart to git…

…hub pages

README.md

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+### Purpose
+
+These example instsructions explain how you would customise one particular dependant Helm chart and publish a newer version to GitHub pages. Instructions assume GitHub pages are already configured for your repo; see the reference section below
+
+### Check Chart.lock file for dependent charts and pull the required version
+For the purpose of this demo, we will select the following service from the `Chart.yaml` file
+```
+- condition: alfresco-sync-service.enabled
+  name: alfresco-sync-service
+  repository: https://alfresco.github.io/alfresco-helm-charts/
+  version: 4.1.0
+```
+```
+1. Delete existing tar file for the sync service. There will be an error pulling the chart otherwise
+rm -rf charts/alfresco-sync-service-4.1.0.tgz
+
+2. Pull a particular version of `alfresco-sync-service` chart
+helm pull alfresco-sync-service --repo  https://alfresco.github.io/alfresco-helm-charts --version 4.1.0 -d charts --untar
+
+3. The above command will pull a tar file called `charts/alfresco-sync-service-4.1.0.tgz` and then untar it into a directory called `alfresco-sync-service`. Delete the tar file
+rm -rf charts/alfresco-sync-service-4.1.0.tgz
+```
+
+### Modify charts
+```
+1. Change the chart version in the newly pulled chart. For example change is from `4.1.0` to `4.1.1`
+2. Make your changes and then test them by upgrading Helm release 
+   - "SECRET=$(openssl rand -base64 20) helm upgrade alfresco-content-services . --values=./values.yaml --set global.tracking.sharedsecret=$SECRET"
+   - NOTE: pods consuming resultant (randomly generated) secrets will have to be restarted
+4. Once satisfied with your changes, create a package and add it to the docs directory
+   - "helm package charts/alfresco-sync-service -d ../docs"
+5. Create / update an index file in docs directory
+   - "helm repo index ../docs --url https://ministryofjustice.github.io/hmpps-delius-alfresco-poc"
+```
+
+### Update the lock file and commit changes
+Locate the `Chart.yaml` file and modify the repository URL and version. It should now look like the code snippet below after the change:
+```
+- condition: alfresco-sync-service.enabled
+  name: alfresco-sync-service
+  repository: https://ministryofjustice.github.io/hmpps-delius-alfresco-poc/
+  version: 4.1.1
+```
+
+1. Delete `charts/alfresco-sync-service` directory as it is no longer needed
+2. Push your changes / docs directory to the feature branch
+3. Update your GitHub pages settings so that the `source branch` is pointing to your feature branch
+4. Update helm dependencies which will pull the updated charts and will update the lock file
+   - `helm dependency update .`
+5. Push the lock file and charts dirctory to the feature branch and get merge approval
+6. Merge into main branch
+6. Update your GitHub pages settings so that the `source branch` is pointing to your main branch
+7. Upgrade the helm release for the changes to be updated in kubernetes cluster
+   - `SECRET=$(openssl rand -base64 20) helm upgrade alfresco-content-services . --values=./values.yaml --set global.tracking.sharedsecret=$SECRET`
+     - NOTE: pods consuming resultant (randomly generated) secrets will have to be restarted
+
+### Alternatively, pull a particular chart either directly from repository URL or by adding it in the local repo
+
+1. Pull a chart with a particular version direcly from the GitHub pages
+- `helm pull alfresco-sync-service --repo  https://ministryofjustice.github.io/hmpps-delius-alfresco-poc/ --version 4.1.1 -d charts --untar`
+
+2. Or add the updated chart in a local helm repo
+```
+helm repo add alfresco-sync-service https://ministryofjustice.github.io/hmpps-delius-alfresco-poc/
+
+helm search repo alfresco-sync-service
+NAME                                            CHART VERSION   APP VERSION     DESCRIPTION          
+alfresco-sync-service/alfresco-sync-service     4.1.1           3.9.0           Alfresco Sync Service
+```
+
+### References to various docs that explain how to set up GitHub pages and how to publish Helm charts
+- [The Chart Repository Guide](https://helm.sh/docs/topics/chart_repository/#github-pages-example)
+- [Chart Releaser Action to Automate GitHub Page Charts ](https://helm.sh/docs/howto/chart_releaser_action/#github-actions-workflow)
+- [Example on how to publish a chart on GitHub pages](https://github.com/technosophos/tscharts)