docs: fix doc types. Add lua type to opts in readme (#2200)

* docs: fix doc types. Add lua type to `opts` in readme

* [pre-commit.ci lite] apply automatic fixes

* chore: fix type error in sidebar.lua

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Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

lua/avante/sidebar.lua

@@ -1613,6 +1613,7 @@ local function calculate_config_window_position()
     end
   end
 
+  ---@cast position -"smart", -string
   return position
 end