GMS-1617: Update ERC1155 readme

contracts/token/erc1155/README.md

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+# ERC 1155 Tokens
+
+This directory contains ERC 1155 token contracts that game studios could choose to use
+directly or extend.
+
+| Contract                | Description                                                                        |
+|-------------------------|------------------------------------------------------------------------------------|
+| preset/ImmutableERC1155 | Provides basic ERC1155 contract that support Burnable, Permit and Royalty features | 
+
+[Read more On the EIP](https://eips.ethereum.org/EIPS/eip-1155)
+
+## ImmutableERC1155
+
+The ImmutableERC1155 contract allows clients to mint multiple different tokens with different token ids within the
+same collection. The contract features methods to allow for minting multiples of multiple token ids to simplify the
+minting flow and reduce gas costs. This contract is built on top of
+the [Openzeppelin implementation of EIP-1155](https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC1155/ERC1155.sol).
+
+### Features
+
+- Permits: Includes the permit method for gasless approvals using ECDSAPermit signatures.
+- Royalties: Implements royalty tracking and retrieval as per the EIP-2981 standard.
+- AccessControl: Provides role-based access control for granting, revoking, and retrieving roles.
+- Base URI: Allows for setting a base URI for all token URIs.
+- Contract URI: Allows for setting a URI for a contract level metadata.
+- Operator Allowlist: Enforces Operator Allowlist to ensure royalties are respected by the operator.
+
+## Status
+
+Contract threat models and audits:
+
+| Description    | Date         | Version Audited                                                                                 | Link to Report                                                                                                    |
+|----------------|--------------|-------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------|
+| Internal audit | Feb 21, 2024 | [b3e2858](https://github.com/immutable/contracts/tree/b3e28586f16cc3759b66a3d825af3b9f78a49783) | [audits/token/202312-threat-model-preset-erc1155.md](../../../audits/token/202312-threat-model-preset-erc1155.md) |
+
+## Architecture
+
+![ImmutableERC1155 Architecture](../../../audits/token/202312-threat-model-preset-erc1155/ImmutableERC1155.jpg)
+
+## Contracts
+
+Following contracts are not intended to be upgradable.
+
+### preset/ImmutableERC1155
+
+The ImmutableERC1155 contract is a version of the Immutable's preset 1155 contract. It has been internally audited and
+is ready to be used. The contract contains all external facing interfaces that are needed to interact(read and write)
+with deployed ERC1155 collections.
+
+### abstract/ERC1155Permit
+
+This is an abstract contract used as an ancestor to the preset 1155. It contains the permit feature for the
+preset, allowing token owners to give approval and permission to a secure and trusted actor. This action is gasless for
+the token owner but will require gas from the approved operator. Please note that using permits in an ERC1155
+collections exposes all the tokens owned by an address to the approved operator. Please double-check to make sure the
+operator is secure and trusted.
+
+### abstract/IERC1155Permit
+
+Provides the required interface for ERC1155Permit.
+
+### abstract/ImmutableERC1155Base
+
+This is another abstract contract used as an ancestor to the preset 1155. It implements many of the internal methods for
+the preset that are not directly public facing for everyday uses. It contains functionalities to update royalties, set
+URIs and manage collection roles.
+