Add Top 25 Most Cited Papers For OA Cliodynamics As A Reading List

[O957]

This PR:

• Uses the tool https://sort-by-citations.streamlit.app/ from this repository I made https://github.com/O957/sort-by-citations to get the top 25 academic works by citation count for different keyword and author searches (pending since I need to complete https://github.com/O957/sort-by-citations/issues/8 and https://github.com/O957/sort-by-citations/issues/5).
• Adds the top 25 academic works for the search term "cliodynamics".
• Adds the top 25 academic works for the search term "Peter Turchin".
• Adds a note in the README on nature of the search results from the OpenAlex API.