fix(nvim-treesitter): set default value of branch option

ensure that `master` branch is used

Author: Hdoc1509

README.md

@@ -155,7 +155,7 @@ Use `install` module instead:
   -- Version or commit of `tree-sitter-vim-map-side`.
   revision = nil,
   -- Branch of `tree-sitter-vim-map-side`.
-  branch = nil,
+  branch = "master",
   custom_fns = {
     -- custom functions with same parameters of `vim.keymap.set()`.
     keymap = {},

lua/vim-map-side/tree-sitter/init.lua

@@ -22,6 +22,8 @@ local M = {}
 ---@type VimMapSide.TS.Opts
 local default_opts = {
   url = "https://github.com/Hdoc1509/tree-sitter-vim-map-side",
+  -- TODO: remove `branch` option. Use `revision` as `branch` too.
+  branch = "master",
   custom_fns = { keymap = {}, modemap = {} },
 }