Undo codepod-io/codepod#349, and add all updates to date.

Rationale:

• It turns out that updating docs together with source code is a rare action.
• Adding docs is an extra burden when submitting a coding PR. I'd prioritize the ease of coding first at this early stage.
• The website contains more than code-related documents, e.g., homepage, team info, etc.
• A separate repo helps separate code and docs PRs.