Update README.md

[mikelibg]

Fixing readme example code for the developers to be able to run the example.
Fixes:

1. missing import to the streamlit package
2. wrong streamlit state name usage
3. wrong node/edge definition
4. wrong parameter name key instead id

[dkapur17]

Hi @mikelibg. Thanks for the PR! The changes look great, except for the addition of the statement importing Streamlit in the first two code blocks, since the script actually wouldn't need that import to run. Adding the statement might give others a sense that it NEEDS to be imported, so I chose to omit it. If you go ahead and make this change, I'll merge the PR.

[mikelibg]

• You are right. Removed the unneeded import.