Fix code and comments inconsistency

[intls]

Motivation

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Change Summary

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Additional Context

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PR-Codex overview

This PR focuses on improving the documentation comments in the Solidity interface files by correcting typos and enhancing clarity.

Detailed summary

• In src/interfaces/IKeyRegistry.sol, the comment for metadata was changed from "Metadata of the signer key." to "Metadata about the signer key."
• In src/interfaces/IIdGateway.sol, the comment for _storageRegistry was corrected from "StorageREgistry" to "StorageRegistry."

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