Add streamlit app

[andrewm4894]

This pull request introduces a new Streamlit app for interacting with Netdata servers and includes several enhancements and updates to existing files. The most important changes include the addition of the Streamlit app, updates to the Makefile, and improvements to the README.md and example.ipynb files.

Addition of Streamlit app:

• app.py: Introduced a new Streamlit app for chatting with Netdata servers, including session state setup, sidebar configuration, conversation rendering, and chat input form.

Updates to Makefile:

• Makefile: Added a new run-app target to facilitate running the Streamlit app. [1] [2]

Enhancements to README.md:

• README.md: Added a new section "App Example" with instructions and an image to demonstrate the Streamlit app usage.

Updates to example.ipynb:

• example.ipynb: Updated execution counts and improved descriptions for various code cells to provide clearer and more detailed examples of Netdata metrics and usage. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]

Configuration updates:

• .streamlit/config.toml: Added a dark theme configuration for the Streamlit app.