Refine explanations and improve formatting in README.md

[derskythe]

Hi, Thanks for the library.
For my part, I would like to offer updated documentation.
In my opinion, in this form it is much easier to read and easier to navigate.

What is done:

• Added missing code blocks
• Changing the format of code examples is was neccessary
• Highlighting variable names and macro names in text
• Refining links to section
• Adjusting the indenting of API documentation listings for better readability

[P-p-H-d]

Thanks a lot for your huge rework on the documentation!

I performed a review of it and find (few) issues in it I have listed below.
By reading the patch I also found some errors in the original documentation :)

[P-p-H-d]

Thank you for your quick taken into account of my remarks.
I have detected another minor issues.