Dev/one pager: docs: update documentation with one-pager quick start guide
Created by: raigal-r
This PR updates the documentation to include a One Pager and a Quick Start Guide on how to execute a transaction using wdk-core.
Changes include:
- Added new one-pager documentation
- Improved documentation about token allowances and gas calculations
These changes address common issues encountered with paymaster configuration and provide better guidance for developers.