Format README.md

[roldugin]

Thank you for the incredible tool, it's a breeze to use. I found it a bit hard to follow the README and took the liberty of formatting it a little.

Summary of changes:

• Add sections, subsections and line breaks where missing
• Turn all inline 1), 2), 3), 4) and a) b) c) d) lists into numbered and bulleted lists respectively
• Turn some lists into subsections to add them to Table of Contents
• Autogenerate Table of Contents
• Replace all HTML tags with Markdown
• Shorten URLs referring to files in the repo (e.g. ![Demo](drawdemo.gif) - note that this left-aligns the image)
• Consistent shortcuts, wrapped in backticks:
  • Ctrl, Shift, Alt, Space, Enter, Del
  • Up, Down
  • Numpad +, Numpad -
  • Shift D, Shift Enter
  • Uppercase T, V, W
  • right click (?)
  • LMB
• Put buttons and tool names in back ticks, while options and concepts in bold. Admittedly not very consistently.
• Misc. formatting and typos

[Shriinivas]

Thank you very much for your effort! Actually, the readme is by no means complete yet. Also many sections still refer to the functionality from the older version of the tool. We will do the formatting once the gaps are filled in and the content is up-to-date. Hope that's OK with you.