update adapter hyperlink and comments about the decoupled architectur…

[rdmcolorz]

…e for post-decoupling

resolves #10386

Problem

[code docs] update ARCHITECTURE.md to reflect changes post-decoupling #10386

Solution

Add hyperlink to the dbt-adapters repo, add comment about the decoupling architecture.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX
• This PR includes type annotations for new and modified functions

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[cla-bot]

Thank you for your pull request and welcome to our community. We could not parse the GitHub identity of the following contributors: Taylor Yang.
This is most likely caused by a git client misconfiguration; please make sure to:

1. check if your git client is configured with an email to sign commits git config --list | grep email
2. If not, set it up using git config --global user.email [email protected]
3. Make sure that the git commit email is configured in your GitHub account settings, see https://github.com/settings/emails

[github-actions]

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