Best platform for documentation about your product

What are you guys using for your products' technical documentation? I am looking for a service, or even a GitHub repo which I can host myself where I can host documentation for my product.

We want to create articles about our product but also want to create a learning center about real-estate (which is the industry we are in)

Ideal requirements are

• Ability to write content in markdown
• show a list of articles by category
• show TOC inside an article
• Follow good SEO practices

I have looked at Zendesk, which is expensive. Also looked at Crisp (which is a messenger and but also has Helpdesk). The problem with Crisp is that the articles are kind of locked in their platform.

What do you guys use?