Improve RST Style

[jakimowb]

Improve the style of RST files using doc8 https://doc8.readthedocs.io/en/latest/readme.html

doc8 helps to detect violations of the following rules:

• invalid RST format - D000
• lines should not be longer than 79 characters - D001
• RST exception: line with no whitespace except in the beginning
• RST exception: lines with http or https urls
• RST exception: literal blocks
• RST exception: rst target directives
• no trailing whitespace - D002
• no tabulation for indentation - D003
• no carriage returns (use unix newlines) - D004
• no newline at end of file - D005

I think all of them make sense and do improve readibitlity, but may be discussed.