misc: add neopyter logo to README.md

[AbaoFromCUG]

Summary

• add a branded logo banner to the top of README.md to improve the plugin's presentation on GitHub
• include the new image assets under doc/ used by the README header

[Copilot]

Pull request overview

Adds a branded logo banner to the top of the repository README to improve GitHub presentation.

Changes:

• Insert a centered logo image at the top of README.md
• Wrap the banner in panvimdoc-ignore markers to avoid affecting generated docs

[Copilot]

The HTML structure here is invalid: an <h1> element shouldn’t wrap a block-level <div>. Consider using a centered <div> (or <p>) that wraps the <img>, or put the <img> directly inside the <h1> without an extra <div>. Also, the img width/height attributes are not valid as written (width/height expect integer pixel values; 300px and auto may be ignored). Prefer width="300" with no height, or use CSS styling if you need auto height.

Suggested change

	<h1><div align="center">
	<img alt="neopyter" width="300px" height="auto" src="./doc/neopyter-with-name.png">
	</div></h1>
	<div align="center">
	<img alt="neopyter" width="300" src="./doc/neopyter-with-name.png">
	</div>