Chinese translation error in the BBCode tag reference table.

**Your Godot version:** v4.8dev

**Issue description:**
There is a Chinese translation error in the img cell in the BBCode tag reference table.
English:
> Add % to the end of {width} or {height} value to specify it as percentages of the control width instead of pixels.

Current Chinese translation:
> 在 {宽度} 和 {高度} 取值的末尾加上 % 可以指定控件宽高的百分比，而不是像素。

Expected Chinese translation:
> 在 {宽度} 和 {高度} 取值的末尾加上 % 可以指定控件宽度的百分比，而不是像素。

"宽高" is wrong. "宽度" is right.

**URL to the documentation page:**
https://docs.godotengine.org/zh-cn/4.x/tutorials/ui/bbcode_in_richtextlabel.html#using-bbcode

Open the Chinese BBCode documentation page at the URL and locate the img cell in the BBCode tag reference table. Change the incorrect “宽高” wording to “宽度”, then verify the rendered Chinese page matches the expected translation.

Written by the indexing model from the issue text.