docs: changed accelerated networking example VMs

[Alwandy]

Due to Standard_D2_v3 not being supported with accelerated network due to 2 vCPUs, the example should use standard_D4_v3 instead.

Reason for Change:
Standard_D2_v3 is not supported with accelerated networking due to 2 vCPUs, changing to D4_v3 on the example makes the example valid.

Issue Fixed:
Fixes #1531

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

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[CecileRobertMichon]

/lgtm

thanks @Alwandy!

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