[charts/portal] Addressing the broken doc links in portal home page and in Api Explorer page

[premchandervodela]

Description of the change

Benefits

Drawbacks

Applicable issues

• fixes #

Additional information

Checklist

• [] Chart version bumped in Chart.yaml according to semver.
• [] 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