fix(float): add fixd option

runtime/lua/vim/_meta/api.lua

@@ -1585,6 +1585,8 @@ function vim.api.nvim_open_term(buffer, opts) end
 ---               • noautocmd: If true then no buffer-related autocommand
 ---                 events such as `BufEnter`, `BufLeave` or `BufWinEnter` may
 ---                 fire from calling this function.
+---               • fixed: If true when anchor is NW or SW, the float window
+---                 would be kept fixed even if the window would be truncated.
 --- @return integer
 function vim.api.nvim_open_win(buffer, enter, config) end