Add editable search box to search results page

[duglin]

Describe the change you'd like to see
From this page: https://knative.dev/docs/
if I enter a search phrase I get a new tab/window with the results.
However, the search phrase is not shown to me on that results page in an editable form. Which means if I had a typo in my search I need to close the window and use the old/previous window. It would be nice if I could just edit the search phrase on this new results page.

Here's what the page looks like now: