Set keymaps in Neovim Lua

Use vim.keymap.set:

-- Map a keybind to a lua function
vim.keymap.set(
    'n',
    '<Leader>lr',
    function()
        vim.lsp.buf.references
    end
)

Takes in four arguments:

1. The mode shorthand, or a table of mode shorthands ({ 'n', 'i', 'v' })
2. The user binding (called left-hand side)
3. What the binding does (called the right-hand side)
4. An optional table of arguments and options

A common option to specify is desc, a long form description of the bind. This is used as an identifier for the keymaps Telescope picker.

For the arguments, see :h map-arguments. For the options, they can be:

• buffer: integer|boolean, for if the mapping should be buffer-local. If true uses current buffer.
• remap: boolean (false), makes the mapping recursive.