Add an edit/request widget to the How-to Guides tab

[cnunciato]

We don't expose this widget on our How-to Guides pages, but we should, or something like it:

Additionally, we should give users who hit the "no guides" path a way to submit a request (or a PR) for a new guide:

This link should probably be shown in all cases --- e.g., if you reach the bottom of the list and haven't found what you were hoping to, we give you somewhere to go next.

[susanev]

related: https://github.com/pulumi/registry/issues/221

[cnunciato]

cc @Brant-Soler as this came up in a discussion today.

[susanev]

hmm, curious what the context was around today's convo?