Add a tpgtools override to add products to the correct website section

[rileykarson]

To group the website sections correctly, we need to supply a legacy-compatible product name in the tpgtools website template. Two examples I'm aware of:

• Compute -> Compute Engine
• Monitoring -> Cloud (Stackdriver) Monitoring

We definitely need an override for cases like formerly-known-as-Stackdriver Monitoring, which we may be able to fix GCE at the DCL level.

[github-actions]

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