drivers: dac: ad3552r : Add README documentation for AD3552R

[analogcay]

Pull Request Description

This is to add README documentation for AD3552R

PR Type

• [ ] Bug fix (change that fixes an issue)
• [ ] New feature (change that adds new functionality)
• [ ] Breaking change (has dependencies in other repos or will cause CI to fail)

PR Checklist

• [ ] I have followed the Coding style guidelines
• [ ] I have complied with the Submission Checklist
• [ ] I have performed a self-review of the changes
• [ ] I have commented my code, at least hard-to-understand parts
• [ ] I have build all projects affected by the changes in this PR
• [ ] I have tested in hardware affected projects, at the relevant boards
• [x] I have signed off all commits from this PR
• [ ] I have updated the documentation (wiki pages, ReadMe etc), if applies

[CLAassistant]

All committers have signed the CLA.

[analogcay]

please squash the two commits and rebase with main branch. there are some other strange changes included in this PR.

This was done, kindly check.

[jvelasc2]

Hi @amiclaus, Will it be fine if I just open a new PR for this?

• Joyce

[analogcay]

New PR was raised for this readme, which has already been merged to main. Closing this PR now.