Add large file download warning and add AzCopy example to upload warning

[diondrapeck]

Description

Please add an informative description that covers that changes made by the pull request and link all relevant issues.

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All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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Testing Guidelines

• [] Pull request includes test coverage for the included changes.

[azure-sdk]

API change check

API changes are not detected in this pull request.