[4.3.0] Modify documentation to fix broken links

[BiyonFernando]

Purpose

To fix broken links in APIM docs.

Goals

Repairing broken links caused by incorrect directories, syntax errors, non-working external links, and unwanted links.

Approach

Approaches taken to fix broken links are as follows:

• Correcting syntax errors in some broken links.
• Removing clickable functionality from example links such as [https://apis.com:9443/].
• Updating incorrect directories in links by referring to previous versions of the documentation.
• Updating the APIM upgrade page to match previous documentation.
• Changing external broken links to functional links.

Release note

Repairing broken links caused by incorrect directories, syntax errors, non-working external links, and unwanted links.

[CLAassistant]

All committers have signed the CLA.