chore: clean docs of expr_expr.R

[etiennebacher]

No description provided.

[eitsupi]

Sorry, but the differences are too large to review. It would be helpful if you could explain the intent of the changes.

[etiennebacher]

Sure, I know this is a lot and I'm not expecting you to review everything. Here are the main changes:

• clean text: fix capitalization, typos, structure of sentences, code formatting, wrap text at 80 characters
• clean tags: use @inheritParams where possible, remove duplicated tags, remove unnecessary tags (e.g @name since this is automatically detected by roxygen2)
• clearer examples: use $with_columns() instead of $select() to show the output side by side with the input, remove unnecessarily long examples
• sometimes some functions were gathered in the same Rd file, so I split them to have one function per file

This is basically the same things I did in other PRs, but this file is massive which explains the number of changes

[eitsupi]

Thanks for the hard work!