Update README.md

[Romazes]

Description

This pull request aims to enhance the README.md file in the Github repository by providing a more descriptive and user-friendly overview of the ThetaData Library. The README content has been updated to better explain the purpose of the library, its key features, and how users can benefit from integrating ThetaData into their trading strategies.

Related Issue

N/A

Motivation and Context

The motivation behind this pull request is to improve the overall user experience for developers and traders who visit the repository. By providing clear and detailed information about the library's capabilities, potential users can quickly understand its value proposition and determine if it aligns with their needs.

Requires Documentation Change

N/A

How Has This Been Tested?

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves implementation)
• Performance (non-breaking change which improves performance. Please add associated performance test and results)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Non-functional change (xml comments/documentation/etc)

Checklist:

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>-<description> or feature-<issue#>-<description>