Add Image Upload Toolkit to Publishing tools

[addozhang]

Hi! I'd like to add my plugin Image Upload Toolkit to the awesome-obsidian list.

What it does:

• Uploads local images embedded in markdown to multiple cloud platforms (Imgur, GitHub, Cloudflare R2, AWS S3, Aliyun OSS, TencentCloud COS, Qiniu Kodo, ImageKit)
• Automatically updates markdown links with the remote URLs
• Perfect for publishing to static sites like GitHub Pages

Why it's useful:

• Solves the common pain point of hosting images when publishing Obsidian notes
• Supports 8 different storage providers with free/affordable options
• 82 stars and actively maintained
• Particularly helpful for users publishing to Jekyll, Hugo, or other static site generators

I've added it to the Publishing section since that's where it fits best. Let me know if you'd like any changes!