Updated ReadMe for Avidemux Github Repository for increased relevance, information, and clarity of the Avidemux application.

[kaimcfarlane]

The original Avidemux ReadMe left out some essential information about the application and omitted key details that would be valuable to both users and developers. This pull request updates the ReadMe to address those gaps in documentation, providing relevant information to enhance user experience and streamline contributions to the Avidemux project.

The following updates/changes were added:

• Enhanced the introduction to the Avidemux application by providing more detailed information, including programming languages used, supported file types, and additional details such as BSD support and free pricing.
• Introduced a table of contents to improve user navigation within the ReadMe.
• Added a link to the official Avidemux website for easy access.
• Created a new "Why Avidemux?" section to emphasize what sets Avidemux apart from other video editing tools.
• Developed a "Main Features" section to showcase the key features users can expect from Avidemux.
• Renamed the "Build" section to "Installation" for better visibility and clarity for developers.
• Included an "Examples" section to provide users with visual examples of Avidemux in action, ensuring proper setup and functionality.
• Added a "Documentation and Support" section to guide users towards available support and updates.
• Created a "Collaborators" section to recognize contributors and encourage community involvement in the project.