Fix: Read The Docs build failed

[tinyAdapter]

This PR fixes the building failure for API docs hosted by Read The Docs. The issue is due to breaking changes in their configuration file format.

Merging this PR will fix the badge in the repo's README.

As an example, I created a testing Read The Docs project to show what the passing doc building looks like:

• Docs: https://ta-singa-test.readthedocs.io/en/latest/
• Badge: https://readthedocs.org/projects/ta-singa-test/badge/