feat: add Transaction filtering info (#134)

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# Description

Add the Transaction Filtering documentation

## Additional context

Add a new block to the transaction lifecycle doc that explains the
possible options to filter the transactions coming from either L1
contracts or API.

content/10.zk-stack/10.components/110.transaction-filtering.md

@@ -0,0 +1,38 @@
+---
+title: Transaction filtering
+description: Learn how to filter transactions on the ZK chain, including L1→L2 and L2 transactions.
+---
+
+The ZK Chain operators can filter both the transactions initiated from L1 and the ones submitted via API directly to L2.
+
+## L1->L2 Transactions
+To filter L1→L2 transactions coming through the Diamond proxy, operators shall:
+
+1. Implement & deploy the `TransactionFilterer` contract which implement the
+   [`ITransactionFilterer`](https://github.com/matter-labs/era-contracts/blob/dev/l1-contracts/contracts/state-transition/chain-interfaces/ITransactionFilterer.sol#L8)
+2. Have the `TransactionFilterer` address set in the state transition
+   [storage](https://github.com/matter-labs/era-contracts/blob/dev/l1-contracts/contracts/state-transition/chain-deps/ZkSyncHyperchainStorage.sol)
+   (by using [this function](https://github.com/matter-labs/era-contracts/blob/dev/l1-contracts/contracts/state-transition/chain-deps/facets/Admin.sol#L95)).
+
+If the filterer exists, it will be called by the
+[Mailbox facet](https://github.com/matter-labs/era-contracts/blob/994897b14eb1d8e77c809da2db3379e7b58125b5/l1-contracts/contracts/state-transition/chain-deps/facets/Mailbox.sol#L239)
+with the tx details, and will return whether the transaction can be executed.
+To disable L1→L2 filtering, the same function that registers the filtered to the storage can be used with `0x0` address.
+
+## L2 Transactions
+
+To filter the transactions sent via the API, operators shall include filtering logic before txs get to the mempool.
+
+To do this, an alternative [`TxSinkLayer`](https://github.com/matter-labs/zksync-era/blob/main/core/node/node_framework/src/implementations/layers/web3_api/tx_sink.rs)
+must be implemented and used by the `node framework` by modifying the code
+[here](https://github.com/matter-labs/zksync-era/blob/main/core/bin/zksync_server/src/node_builder.rs#L230).
+For reference,
+
+- See [Node Framework example](https://github.com/matter-labs/zksync-era/blob/main/core/node/node_framework/examples/main_node.rs#L416)
+- See [example implementation](https://github.com/matter-labs/zksync-era/pull/1782)
+
+#### Note on Withdrawals
+
+Imagine a case where a user deposited funds and then was added to the denylist or removed from the allowlist.
+In that scenario, the user may have their funds locked on the L2 or potentially even in a contract on the L2.
+Please think about handling such cases and ensuring that the user can still withdraw their funds.