Update docs ref deprecated type `KonaHandleRegister`

[emhane]

Update docs referencing deprecated type KonaHandleRegister

kona/docs/docs/pages/sdk/proof/exec-ext.mdx

Lines 6 to 9 in 4733473

	To register a custom handler, for example to add a custom precompile, modify the behavior of an EVM opcode,
	or change the fee handling, `StatelessL2BlockExecutorBuilder::with_handle_register` is your friend. It accepts a
	[`KonaHandleRegister`](https://docs.rs/kona-executor/latest/kona_executor/type.KonaHandleRegister.html), which
	can be used to take full advantage of [`revm`'s Handler API](https://github.com/bluealloy/revm/blob/f57e3e639ee157c7e659e740bd175a7357003570/documentation/src/crates/revm/handler.md#handler).

https://github.com/op-rs/kona/actions/runs/17097895931/job/48486594111?pr=2689#step:3:817

[Peponks9]

Hi @emhane, would like to contribute to this one if possible :)

[emhane]

hey @Peponks9 ! nice! recommend choosing any issue labelled good-first-issue.

[Peponks9]

hey @emhane, yes i've been looking for good-first-issue but i found most of them with assignees or a pull request linked already. Also, i'm good to go with this issue, right?

[emhane]

I'm not sure if it's evident which type has replaced KonaHandleRegister, hence didn't mark this as good first issue. if you have an idea, pls feel free to work on it. also recommend checking op-alloy, alloy and reth repos for good first issues!