DOCS: Trailing commas

[cafferata]

Fixes #2850.

Deeplink to the preview link:
https://docs.dnscontrol.org/~/revisions/b85k9WvN3UMndgrP20mT/advanced-features/code-tricks#trailing-commas

[tlimoncelli]

I'm not sure people will understand the + and - notation. Maybe some other way to show the change?

[cafferata]

Do you think this before/after is better to read?

https://docs.dnscontrol.org/~/revisions/nq5DciQrXbsjh0WlQ129/advanced-features/code-tricks#trailing-commas

https://docs.dnscontrol.org/~/revisions/y0IsGj9o86nJZkynay3Q/advanced-features/code-tricks#trailing-commas

[tlimoncelli]

yes! The "before vs. after" is much more readable.

I'd add some narrative after the "after" to explain the benefit. Maybe something like: Suppose you want to add a new record after the "bar" line. In the "before" example, the diff would show the addition of the comma on the "bar" line plus the new record you added. In the "after" example the diff would be just the added record. This creates PRs that are easier to approve.

(Feel free to reword that! It's just the first thing that came to my head.)

[cafferata]

Great! I've added two commits:

1. A introduction to trailing commas.
2. Version-control diffs examples based on the code examples.

What do you think of this version?
https://docs.dnscontrol.org/~/revisions/lvH3LKLmIEEQOXJyYvIs/advanced-features/code-tricks#trailing-commas

[tlimoncelli]

Hey that's great! Thanks!