The SQLite documentation is available in the Download page here.
as of today, the search paragraph is:
Documentation
sqlite-doc-3100200.zip
(5.13 MiB) Documentation as a bundle of static HTML files.
(sha1: d6d61ad65e7e1700992c51a61209670571fa7908)
Of course, this will change, but you now have a hint to where can I download the whole SQLite documentation ?".