Update MANUAL.txt to remove false info on Lua mode not supporting -i

[iandol]

Current pandoc-lua does support REPL and -i as far as I understand.

[jgm]

I also note

% pandoc lua -h
pandoc: user error (unrecognized option `-h'
Usage: pandoc lua [options] [script [args]]
  -e stat    execute string 'stat'
  -i         interactive mode -- currently not supported
  -l mod     require library 'mod' into global 'mod';
             if 'mod' has the pattern 'g=module', then
             require library 'module' into global 'g'
  -v         show version information
  -E         ignore environment variables -- partially supported
  -W         turn warnings on -- currently not supported
)

@tarleb where is that message "interactive mode -- currently not supported" defined? We should change that.

[tarleb]

Oh, thanks. I fixed it here: https://github.com/hslua/hslua/blob/main/hslua-cli/src/HsLua/CLI.hs#L248