Add lightweight feedback capability to each page in the docs

[hillaryfraley]

Description

We added a one-click rating scale to the docs in #3076 and moved it up to the sidebar in #3115.

We would like to enhance this with a lightweight feedback form that appears for any rating except five hearts so we can capture users' thoughts about any difficulties they have with any particular docs pages.

Category

This is an issue with:

• bug (bug in site build, layout, or functionality)
• enhancement (add new or updated site functionality)

Affected pages

All pages

Expected behavior

When users provide any rating except five hearts, they see a brief feedback form that requests a few lines of anonymous feedback about what went wrong, what to improve, etc.

When a user submits feedback with this form, the feedback is saved such that:

• The feedback is connected with the page from which it was submitted
• The Reliability team can access the feedback and act on it

Current behavior

Users must open a GitHub issue or PR to share feedback about a docs page.

Changes needed

Add the form -- I've tinkered with an onclick event to add something like "Thank you!" but didn't get any further.

Additional context

I think we should aim for something like the form Microsoft uses when users click thumbs up/thumbs down: https://docs.microsoft.com/en-us/dynamics365/customer-service/learning-catalog

[hillaryfraley]

another good example with thumbs up/down and optional comment field (scroll to bottom of page): https://developer.aiven.io/