Clippy fixes from stable and nightly (#13455)

- **Doccomment style fixes**
- **Forgotten stuff in `nu-pretty-hex`**
- **Don't `for` around an `Option`**
- and more

I think the suggestions here are a net positive, some of the suggestions
moved into #13498 feel somewhat arbitrary, I also raised
https://github.com/rust-lang/rust-clippy/issues/13188 as the nightly
`byte_char_slices` would require either a global allow or otherwise a
ton of granular allows or possibly confusing bytestring literals.

crates/nuon/src/from.rs

@@ -12,7 +12,7 @@ use std::sync::Arc;
 /// > **Note**  
 /// > [`Span`] can be passed to [`from_nuon`] if there is context available to the caller, e.g. when
 /// > using this function in a command implementation such as
-/// [`from nuon`](https://www.nushell.sh/commands/docs/from_nuon.html).
+/// > [`from nuon`](https://www.nushell.sh/commands/docs/from_nuon.html).
 ///
 /// also see [`super::to_nuon`] for the inverse operation
 pub fn from_nuon(input: &str, span: Option<Span>) -> Result<Value, ShellError> {