[charts/portal]51doc changes

Description of the change

Doc changes for Portal 51 release

Benefits

Drawbacks

Applicable issues

Additional information

Checklist

[x] Chart version bumped in Chart.yaml according to semver.
[x] Variables are documented in the README.md
[x] Title of the PR starts with chart name (e.g. [charts/gateway])
[x] If the chart contains a values-production.yaml apart from values.yaml, ensure that you implement the changes in both files

CAAPIM / apim-charts