Open readme when the project opens in vscode

[Ahrjen]

This pull request includes changes to improve the functionality and activation of the readme-auto-open extension. The key changes involve modifying the activation events and enhancing the logic to automatically open the readme.md file if it exists in the workspace.

Improvements to extension activation:

• package.json: Added an activation event to trigger the extension when a readme.md file is detected in the workspace. Removed the predefined command from the commands section.

Enhancements to extension functionality:

• src/extension.ts: Simplified the activation log message and added logic to check for the existence of readme.md files in various capitalizations. If a readme.md file is found, it is opened automatically, and a flag is set to indicate that the user has seen the readme.

Resolves #5

[Ahrjen]

Implemented

• Async await
• Readme.*
• Easier if
• Use built-in findFiles instead of forEach
• Better logging

Tested

• 1 workspace folder (readme is opened once)
• 1 workspace with multiple workspace folders (any readme in workspace folder roots are opened once)
• Empty workspace (no errors thrown, activationEvent does not find a readme, so extension.ts is not executed)
• 1 file in empty workspace (no errors thrown, activationEvent does not find a readme, so extension.ts is not executed)