Documentation Update For WAMR's New Home

[woodsmc]

This is a documentation update that reflects that WAMR will no longer be a Bytecode Alliance project. This PR updates the documentation in three key ways:

1. It removes references to the Bytecode Alliance and statements that this is a Bytecode Alliance project.
2. It inherits the security practices that WAMR previously operated under as part of the Bytecode Alliance. Modified to reflect that this is now a WAMR only practice.
3. It inherits the code of conduct that WAMR previously operated under as part of the Bytecode Alliance. Modified to reflect that this is now a WAMR only practice.

Note: This does not change the URLs in the documentation. This ensures that this PR can be committed ahead of the migration. A further PR will be required to update the URLs.

This early change is designed to allow review and approval of the above changes.