Added 12-text-editing.md and some images (#43)

* Update README.md

* Adds Markdown guide and image asset

Introduces documentation on text editing with Markdown.

LaTeX, and Typst hadn't introduced yet.

Includes a new image asset for visual support.

* 新增 LaTeX 示例图片和文档信息

* 更新 LaTeX 文档，添加下级标题和公式展示示例

* 更新 12-text-editing.md，添加 AMS 系列、geometry、graphicx、listings、algorithm2e 和 cases 宏包的使用说明

* 删除不再使用的 LaTeX 示例图片，并更新文档内容以增加对 `beamer` 和 `report` 包的介绍

* Update .nvmrc

* 删除 README.md 中的 Fork 说明, 并进行prettier

* doc: final doc 12 added

* doc: doc12 final commit

* doc: a little refresh

* doc: avoiding a bug of prettier

* doc; doc12 slightly changed as requested

* doc: doc12 slightly changed as requested

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Co-authored-by: 炫懿 臧 <[email protected]>
Co-authored-by: Li Bohai <[email protected]>
Co-authored-by: 炫懿 臧 <�[email protected]>
Co-authored-by: 炫懿 臧 <�[email protected]>

Author: 5 people