[Docs] Fix PATH config file location

[red-0ne]

Summary

This PR includes updates to the docusaurus/docs/operate/quickstart/gateway_cheatsheet.md file to correct the configuration file path and improve the instructions for setting up the Shannon configuration.

Documentation updates:

• Changed the path for generating a default Shannon config from cmd/.config.yaml to config/.config.yaml.
• Updated sed commands to reflect the new configuration file path config/.config.yaml instead of cmd/.config.yaml.
• Adjusted the build and run instructions for the PATH Gateway to use a more direct build command.

Issue

PATH changed its config file location from cmd/ to config/ directory which needs to be reflected in the gateway_cheatsheet documentation.

Type of change

Select one or more from the following:

• New feature, functionality or library
• Consensus breaking; add the consensus-breaking label if so. See [Infra] Automatically add the consensus-breaking label #791 for details
• Bug fix
• Code health or cleanup
• Documentation
• Other (specify)

Testing

• Documentation: make docusaurus_start; only needed if you make doc changes

Sanity Checklist

• I have tested my changes using the available tooling
• I have commented my code
• I have performed a self-review of my own code; both comments & source code
• I create and reference any new tickets, if applicable
• I have left TODOs throughout the codebase, if applicable

[red-0ne]

Closing in favor of #982