[skip ci] update compulsoriness of NEXT_PUBLIC_ROLLUP_L2_WITHDRAWAL_URL in the docs

Author: tom2drum

docs/ENVS.md

@@ -389,7 +389,7 @@ This feature is **enabled by default** with the `coinzilla` ads provider. To swi
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 | NEXT_PUBLIC_ROLLUP_TYPE | `'optimistic' \| 'shibarium' \| 'zkEvm' \| 'zkSync' ` | Rollup chain type | Required | - | `'optimistic'` |
 | NEXT_PUBLIC_ROLLUP_L1_BASE_URL | `string` | Blockscout base URL for L1 network | Required | - | `'http://eth-goerli.blockscout.com'` |
-| NEXT_PUBLIC_ROLLUP_L2_WITHDRAWAL_URL | `string` | URL for L2 -> L1 withdrawals | - | - | `https://app.optimism.io/bridge/withdraw` |
+| NEXT_PUBLIC_ROLLUP_L2_WITHDRAWAL_URL | `string` | URL for L2 -> L1 withdrawals | Required only for `optimistic` rollups | - | `https://app.optimism.io/bridge/withdraw` |