Improve overall APK documentation

[sgayangi]

QSG

• The link to the Prerequisites page should open in a new tab.
• The link to the FAQs page should open in a new tab
• Link from the QSG directly to the deployment section in the FAQs
• Update the section about all the pods transitioning to the running state - that api-admissions should be in Completed state.
• Make the JSON file auto download when the link is clicked.

Prerequisites

• There needs to be a paragraph detailing the tools needed under the Prerequisites heading.
• The links to kubectl, Helm and cluster installations should open in new tabs.
• Explain the dependencies in the page and provide the links for installation.
• Explain the use of PostgreSQL for QSG.
• Fix typo: "manage kubernetes" -> "managed kubernetes"
• In the "Other dependencies" section, clarify the dependencies needed and their necessity in the installation.
• Explain why the Docker Engine version is specified

Helm Chart

• Link the Discord channel in the Helm chart

FAQs

• Show the FAQs sections on the left side
• The link to the Customize Configs page should open in a new tab

Others

• Update all links so that new tabs are opened as needed.
• In header modification, link the approaches to apk-conf and CRs.

QSG Backend

• Update the QSG backend: change the GET /employee route to GET /employees