Good First Docs: Explain how to run examples

[exploreriii]

Problem

We should explain how to run examples as a new section in running examples.md

Dosik said it nicely..

# Due to the way the script is structured, it must be run as a module
# from the project root directory
# Run from the project root directory
python -m examples.contract_delete

Then double check all example scripts are running with that command

Solution

Document and explain the command to execute examples

Remind the user they need a hedera testnet account
Ensure they are using the correct keys

Alternatives

No response

[exploreriii]

This is being tackled in #304