Oops I typoed a url, but the problem is real.
Again:
The search at
https://www.postgresql.org/docs/10/static/index.html
does not find anything.
The produced url is: https://www.postgresql.org/search/?u=%2Fdocs%2F10%2F&q=select
which (apparently) should be: https://www.postgresql.org/search/?u=%2Fdocs%2F10.0%2F&q=select
i.e., s/10/10.0/
Erik Rijkers