chore(docs): add docs

lua/gopher/json2go.lua

@@ -1,9 +1,25 @@
+---@toc_entry json2go
+---@tag gopher.nvim-json2go
+---@text
+--- Convert json to go type annotations.
+---
+---@usage
+--- `:GoJson` opens a temporary buffer where you can paste or write JSON.
+--- Saving the buffer (`:w` or `:wq`) automatically closes it and inserts the
+--- generated Go struct into the original buffer at the cursor position.
+---
+--- Alternatively, you can pass JSON directly as an argument:
+--- >vim
+---    :GoJson {"name": "Alice", "age": 30}
+--- <
+
 local c = require "gopher.config"
 local log = require "gopher._utils.log"
 local u = require "gopher._utils"
 local r = require "gopher._utils.runner"
 local json2go = {}
 
+---@dochide
 ---@param bufnr integer
 ---@param cpos integer
 ---@param type_ string
@@ -16,10 +32,17 @@ local function apply(bufnr, cpos, type_)
   vim.api.nvim_buf_set_lines(bufnr, 0, -1, true, lines)
 end
 
----@param json_str string
----@return string?
+-- Convert json string to go type.
+---
+---@param json_str string Json string that is going to be converted to go type.
+---@return string? Go type, or nil if failed.
 function json2go.transform(json_str)
-  local rs = r.sync({ c.commands.json2go }, { stdin = json_str })
+  local cmd = { c.commands.json2go }
+  if c.json2go.type_name then
+    table.insert(cmd, "-type", c.json2go.type_name)
+  end
+
+  local rs = r.sync(cmd, { stdin = json_str })
   if rs.code ~= 0 then
     u.notify("json2go: got this error: " .. rs.stdout, vim.log.levels.ERROR)
     log.error("json2go: got this error: " .. rs.stdout)
@@ -28,13 +51,15 @@ function json2go.transform(json_str)
   return rs.stdout
 end
 
+---@dochide
+---@param ocpos integer
 local function interactive(ocpos)
   local obuf = vim.api.nvim_get_current_buf()
   local owin = vim.api.nvim_get_current_win()
 
   -- setup the input window
   local buf = vim.api.nvim_create_buf(false, true)
-  vim.api.nvim_command "vsplit" -- TODO: make it configurable
+  vim.cmd(c.json2go.interactive_cmd)
 
   local win = vim.api.nvim_get_current_win()
   vim.api.nvim_win_set_buf(win, buf)
@@ -89,6 +114,10 @@ local function interactive(ocpos)
   vim.cmd "startinsert"
 end
 
+--- Converts json string to go type, and puts result under the cursor. If
+--- [json_str] is nil, will open an interactive prompt (with cmd set in
+--- config).
+---
 ---@param json_str? string
 function json2go.json2go(json_str)
   local cur_line = vim.api.nvim_win_get_cursor(0)[1]