Fix custom checkbox type annotation

Author: MeanderingProgrammer

lua/render-markdown/custom_checkbox.lua

@@ -6,7 +6,6 @@ local M = {}
 ---@return render.md.CustomCheckbox?
 M.get_exact = function(value)
     for _, checkbox in pairs(state.config.checkbox.custom) do
-        ---@diagnostic disable-next-line: undefined-field
         if checkbox.text == value then
             return checkbox
         end
@@ -18,7 +17,6 @@ end
 ---@return render.md.CustomCheckbox?
 M.get_starts = function(value)
     for _, checkbox in pairs(state.config.checkbox.custom) do
-        ---@diagnostic disable-next-line: undefined-field
         if vim.startswith(value, checkbox.text) then
             return checkbox
         end

lua/render-markdown/init.lua

@@ -49,7 +49,7 @@ local M = {}
 ---@class render.md.UserCheckbox
 ---@field public unchecked? string
 ---@field public checked? string
----@field public custom? table<string, render.md.CustomCheckbox[]>
+---@field public custom? table<string, render.md.CustomCheckbox>
 
 ---@class render.md.UserConfig
 ---@field public start_enabled? boolean

lua/render-markdown/types.lua

@@ -31,7 +31,7 @@
 ---@class render.md.Checkbox
 ---@field public unchecked string
 ---@field public checked string
----@field public custom table<string, render.md.CustomCheckbox[]>
+---@field public custom table<string, render.md.CustomCheckbox>
 
 ---@class render.md.Config
 ---@field public start_enabled boolean