## What changes were proposed in this pull request?

- Provides correct description of the semantics of a `dict` argument passed as `to_replace`.
- Describes type requirements for collection arguments.
- Describes behavior with `to_replace: List[T]` and `value: T`

## How was this patch tested?

Manual testing, documentation build.

Author: zero323 <zero323@users.noreply.github.com>

Closes #16792 from zero323/SPARK-19453.