Fold in MD in write-ups into docs

**Is your feature request related to a problem? Please describe.**
We have https://github.com/apache/hamilton/tree/main/writeups that has various markdown files.
This is duplicative of documentation.

**Describe the solution you'd like**
We should delete them and make sure their content is represented in the main documentation & examples.

**Describe alternatives you've considered**
N/A

**Additional context**
[This issue was created for comment](https://github.com/apache/hamilton/issues/1186#issuecomment-3325192011)