missing-whitespace-around-operators comment (#6106)
**Summary**
Updated doc comments for `missing_whitespace_around_operator.rs`. Online
docs also benefit from this update.
**Test Plan**
Checked docs via
[mkdocs](https://github.com/astral-sh/ruff/blob/389fe13c934fe73679474006412b1eded4a2cad0/CONTRIBUTING.md?plain=1#L267-L296)
