docs: add notes to firmware on-boarding instructions

[reubenmiller]

Proposed changes

Add a note about the on-boarding instructions under the firmware section for tips on using the c8y-tedge go-c8y-cli extension.

Also update the c8y tedge scan command output example to reflect the current state of the c8y-tedge output (where the mdns suffix was added to each of the detected devices)

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
• Documentation Update (if none of the other choices apply)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s)
• I ran cargo fmt as mentioned in CODING_GUIDELINES
• I used cargo clippy as mentioned in CODING_GUIDELINES
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
508	0	2	508	100	1h29m34.052562999s

[didier-wenzek]

Approved