Fixes #3054 .

Description

This PR fixed the broken link the API docs.
The root cause is that Sphinx document can't correctly parse a link for markdown file, so I put the raw link for users directly.

Status

Ready/

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.