Docs: Improve grammar, consistency, and clarity in ERC-20, ERC-1155, and Backwards Compatibility guides

[Pronoss]

This PR improves the clarity, grammar, and consistency of the following documentation files:

• backwards-compatibility.adoc
• erc1155.adoc
• erc20-supply.adoc
• erc20.adoc

Key Improvements:

• Fixed grammar (e.g., added missing commas, corrected "whilst" to "while")
• Standardized phrasing (e.g., "OpenZeppelin Contracts provide" instead of "provides" where appropriate)
• Improved clarity in complex sentences for better readability
• Reworded misleading or ambiguous statements without altering technical meaning
• Formatted large numbers with commas for better readability (e.g., 350k → 350,000)
• Consistent usage of Oxford commas where needed

These changes help ensure the documentation is more accessible, clear, and consistent for users.