Implement a simple feedback tool to gather feedback from developers

[juanmaguitar]

At https://wiki.mutable.ai/WordPress/gutenberg they have a simple feedback tool using the following icons 👍👎 to redirect to a form where users can provide feedback about the documentation.

Example of the form:
https://docs.google.com/forms/d/e/1FAIpQLSeUPwFsVgAIuprLzhVFU_F8m3qq7-J2_X0WX5M5MXjxxXLcfw/viewform?entry.1406724461=This+section&entry.433681862=WordPress%2Fgutenberg%23interactivity-api

The impact of this task would be big as it would enable a direct feedback loop about the docs that are not currently available.

cc: @ndiego