Update README to improve clarity and add missing sections

[shashankrushiya]

Closes #

Description

Title: Improve README Documentation and Structure

Description:
This PR enhances the readability and structure of the README.md file for the GraphQL website repository. The changes aim to make the documentation more user-friendly and accessible, particularly for new contributors. Below is a summary of the improvements:

• Table of Contents: Added to improve navigation within the README.
• Overview Section: Rephrased for clarity, explaining GraphQL's purpose more effectively.
• Deployment Instructions: Expanded with steps for running the site locally.
• Contribution Guidelines: Organized the CLA process steps for easier comprehension.
• Financial Support: Added details on supporting the GraphQL Foundation.

These updates help streamline the onboarding process for contributors and provide a clearer understanding of the project and its goals.

Type of change:

• Documentation enhancement

Checklist:

• I've read the contributing guidelines
• My changes improve the documentation structure and clarity
• I’ve tested the deployment instructions locally

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: benjie / name: Benjie (bb4ee0d, 7721c3a, 1e7bb60)
• ✅ login: shashankrushiya / name: Shashank (689d71e)

[vercel]

@shashankrushiya is attempting to deploy a commit to the The GraphQL Foundation Team on Vercel.

A member of the Team first needs to authorize it.

[benjie]

Thanks; these changes look good! I've suggested a few edits below

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
graphql-github-io	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 21, 2024 2:29pm

[shashankrushiya]

Hi @benjie, thank you for implementing the changes; they look great!