Based on the text, I would think it gets used on https://matplotlib.org/stable/search.html and https://matplotlib.org/mpl-third-party/search.html, but we have a copy downstream at https://github.com/matplotlib/matplotlib/blob/main/doc/_templates/search.html without one in mpl-third-party. And that additional text really seems to only make sense on the main repo, not mpl-third-party, so it's good to remove it here.