Add openzeppelin audit report to the repo (#258)

This PR:
- Implements #233

modules/4337/README.md

@@ -243,6 +243,7 @@ npx hardhat --network <network> etherscan-verify
 ## Audits
 
 - [For version 0.1.0 by Ackee Blockchain](docs/v0.1.0/audit.md)
+- [For version 0.2.0 by Multiple Auditors](docs/v0.2.0/audit.md)
 
 ## Security and Liability
 

modules/4337/docs/v0.2.0/audit.md

@@ -1,10 +1,12 @@
 # Audit Results
 
-## Auditor
+## Audit 1
+
+### Auditor
 
 Ackee Blockchain (<https://ackeeblockchain.com/>).
 
-## Notes
+### Notes
 
 The final audit was performed on commit [25779b5a5077e109a585993a02c4dad2209ab084](https://github.com/safe-global/safe-modules/tree/25779b5a5077e109a585993a02c4dad2209ab084).
 
@@ -16,6 +18,22 @@ There is one acknowledged finding from the audit report:
   > - The most critical functionality, such as signature checks and replay protection, is handled by the Safe and Entrypoint contracts.
   > - The entrypoint contract uses the optimizer.
 
-## Files
+### Files
 
 - [Final audit report](audit-report-v2.0.pdf)
+
+## Audit 2
+
+### Auditor
+
+OpenZeppelin (<https://openzeppelin.com/>).
+
+### Notes
+
+The final audit was performed on commit [3853f34f31837e0a0aee47a4452564278f8c62ba](https://github.com/safe-global/safe-modules/tree/3853f34f31837e0a0aee47a4452564278f8c62ba).
+
+No issues were reported related to the module's business logic, but we have implemented some of the suggested optimisations from the audit report into the codebase. These changes will be included in the next release of the 4337 module. For more information about the audit findings, please refer to the report.
+
+### Files
+
+- [Final audit report](audit-report-openzeppelin.pdf)