Where can I download the Lua 5.1's manual?

[Niccolo Medici <niccolomedici@...>]

I'm talking about the documentation you see at https://www.lua.org/manual/5.1/ .

I'm often off-line so I want to have the documentation on my own computer.

The documentation that comes in Lua 5.1's tarball doesn't contain all
the functions (e.g., 'lua_isnoneornil' is missing, from both
contents.html and manual.html).

I know I can crawl-download the documentation from
https://www.lua.org/manual/5.1/ with a tool like wget but I thought to
ask first if there's a more straightforward way.