fix(docs): config requires ignore_methods field (#98)

* fix(settings): typo in type annotations

* fix(settings): make methods field optional

lua/mason-null-ls/settings.lua

@@ -9,7 +9,7 @@ local M = {}
 
 ---@class MasonNullLsSettings
 ---@field handlers table | nil
----@field ignore_methods MasonNullLsMethods
+---@field methods MasonNullLsMethods | nil
 ---@field ensure_installed table
 ---@field automatic_installation boolean | table
 local DEFAULT_SETTINGS = {