Update EIP-7201: Add note about Solidity compiler version

Merged by EIP-Bot.

EIPS/eip-7201.md

@@ -30,7 +30,7 @@ A _namespace id_ is a string that uniquely identifies a namespace in a contract.
 
 The storage location for a namespace is defined as `ns_loc(id: string) = keccak256(uint256(keccak256(id)) - 1)`.
 
-A Solidity contract using namespaced storage can annotate a struct with the NatSpec tag `@custom:storage-location erc7201:<NAMESPACE_ID>` to identify it as a namespace with id `<NAMESPACE_ID>`.
+A Solidity contract using namespaced storage can annotate a struct with the NatSpec tag `@custom:storage-location erc7201:<NAMESPACE_ID>` to identify it as a namespace with id `<NAMESPACE_ID>`. _(Note: The Solidity compiler includes this annotation in the AST since v0.8.20, so this is recommended as the minimum compiler version when using this pattern.)_
 
 ## Rationale
 
@@ -54,7 +54,7 @@ No backward compatibility issues found.
 ## Reference Implementation
 
 ```solidity
-pragma solidity ^0.8.19;
+pragma solidity ^0.8.20;
 
 contract Example {
     /// @custom:storage-location erc7201:example.main