Update README.md to prioritize DefaultAzureCredential/TokenCredential.

[diberry]

Is your feature request related to a problem? Please describe.
Update the readme so I know DAC is provided and show sample code of how to use it. If the readme doesn't offer DAC, I have to look at the package.json or the ref docs to figure it out.

Describe the solution you'd like
A clear and concise description of what you want to happen. Update any README.md for SDKs to prioritize DAC. I'll attach a MD file will packages which seem to have DAC but don't mention it in the README.md

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
DAC.md

@scottaddie @hector-norza

[diberry]

Can this morning also it into the npm packages listing that is merged into JS Dev Center as another column?