Program security - Closing accounts lesson updated

[0xCipherCoder]

Problem

Summary of Changes

• Updated code snippets with the latest anchor version
• Fixed content with updated version changes
• Fixed grammar and styling
• Fixed as per guidelines

References - https://github.com/coral-xyz/anchor/pull/2726 https://github.com/coral-xyz/anchor/blob/master/lang/src/common.rs

Fixes #

Unboxed PRs Starter - https://github.com/solana-developers/closing-accounts/pull/1 Solution - https://github.com/solana-developers/closing-accounts/pull/2

[0xCipherCoder]

@mikemaccana Please review this once. Let me know if any suggestions.

[github-actions[bot]]

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