Add more ways to create a PathBuf to docs
Add more ways to create a PathBuf to docs

The best way to do this wasn't in the documentation, and the ways that
were there needed some extra text to elaborate.

Fixes #40159

aidancully/rust,GBGamer/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust