Provide a llms.txt

### What is the issue?

More people are using AI-based tools for development. In order to provide the best, up-to-date information I want to propose to provide a llms.txt that can be added as context in your prompts and development flow.

Most projects provide this as a public txt file at their main domain, e.g. soliditylang.org/llms.txt altho I would suggest this under the `/.well-known/` subdir.

Especially for Solidity development, I think its important that generated code is correct, safe and uses recommended best practices. While it obviously provides no guarantees, I think having an up-to-date context for different major versions and compiler versions can helpful to provide a safe environment to experiment with AI-generated code

More info https://llmstxt.org/

Examples
- https://docs.scaffoldeth.io/llms-full.txt
- https://docs.reown.com/llms.txt
- https://llmstxt.site/

Start by reviewing the llmstxt.org guidance and the linked example files, then determine the intended public location between /llms.txt and /.well-known/. The work is done when the repository provides an up-to-date context file covering the relevant Solidity and compiler-version guidance; no repository files or tests are named in the issue.

Written by the indexing model from the issue text.