This pull request formally signs David Sonnet's Individual Contributor License Agreement for Odoo. This ensures compliance with Odoo's licensing terms and allows David to contribute to the project. The addition of the `dsonnet.md` document provides the necessary legal documentation.

Signing the Odoo Individual Contributor License Agreement v1.0.

Adds `doc/cla/individual/dsonnet.md`.

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I confirm I have read the PR guidelines at www.odoo.com/submit-pr