Update example using outdated type `L1BlockInfoGlacier`

[emhane]

kona/docs/docs/pages/sdk/examples/new-l1-block-info-tx-hardfork.mdx

Lines 64 to 103 in 4733473

	## Protocol Changes
	Introduce a new `glacier.rs` module containing a `L1BlockInfoGlacier` type
	in [`kona_genesis::info` module][info-mod].
	This should include a few methods used in the `L1BlockInfoTx` later.
	```rust
	pub fn encode_calldata(&self) -> Bytes { ... }
	pub fn decode_calldata(r: &[u8]) -> Result<Self, DecodeError> { ... }
	```
	Use other hardfork variants like the [`L1BlockInfoEcotone`][ecotone]
	for reference.
	Next, add the new "Glacier" variant to the [`L1BlockInfoTx`][info-tx].
	```rust
	pub enum L1BlockInfoTx {
	...
	Glacier(L1BlockInfoGlacier)
	}
	```
	Update [`L1BlockInfoTx::try_new`][try-new] to construct the `L1BlockInfoGlacier`
	if the hardfork is active using the `RollupConfig::is_glacier_active`.
	Also, be sure to update [`L1BlockInfoTx::decode_calldata`][decode-calldata]
	with the new variant decoding, as well as other [`L1BlockInfoTx`][info-tx]
	methods.
	Once some tests are added surrounding the decoding and encoding of the new
	`L1BlockInfoGlacier` variant, all required changes are complete!
	Now, [this example PR diff][pr-diff] introducing the Isthmus changes should
	make sense, since it effectively implements the above changes for the Isthmus
	hardfork (replacing "Glacier" with "Isthmus"). Notice, Isthmus introduces
	some new "operator fee" fields as part of it's `L1BlockInfoIsthmus` type.
	Some new error variants to the [`BlockInfoError`][bie] are needed as well.

https://github.com/op-rs/kona/actions/runs/17097895931/job/48486594111?pr=2689#step:3:809