Update README with detailed information

[aeisenberg]

Update README.md to include detailed information about inputs, workflow permissions, build modes, and actions.

• Inputs: Add a section on inputs, including the config option, languages, queries, packs, db-location, ram, threads, and source-root.
• Workflow Permissions: Add a section on workflow permissions required for the actions.
• Build Modes: Add a section explaining the different build modes available for the actions (none, autobuild, manual).
• Actions: Add a section describing the different actions (init, autobuild, analyze, upload-sarif, resolve-environment, start-proxy) and how to use them, with links to the relevant documentation on GitHub.

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For more details, open the Copilot Workspace session.

[aeisenberg]

Please ignore for now. I created this PR using a copilot workspace. There are a lot of things I need to clean up. I just wanted to try out using it.

[angelapwen]

@aeisenberg just checking, is this PR ready for review by a human or not yet? 🤖

[aeisenberg]

It needs some more work. I haven't had a chance to really look at it. I'm not sure when I'll get another chance, so if you want to pick it up, feel free to.

[angelapwen]

Ah, was just wondering if you were blocked on review 😸

[aeisenberg]

@angelapwen This is now ready for review. Can you take a look when you have a chance?