docs: fixing trailing commas in `configuration.mdx` (#8596)
### Description
Fixes #8582.
Removed trailing commas where not needed and added where needed.
### Additional infos
Honestly this was a blind fix, I tried to run docs locally following
`contributing` and `troubleshooting`, installed `go`, `capnp`, and all
other packages, but I always run in some sort of problem.
`pnpm docs` opened `https://www.npmjs.com/package/cli` on the browser,
sometimes i had
> × No package found with name 'docs' in workspace
I'm sorry if I wasn't able to follow a real contribution steps, if
someone can help me go through this I will be happy for this and future
contribution.
Have a nice day!
