Add information about Code quality tests in guidelines

[czgdp1807]

Description of the problem

After merging #72 the code quality is checked via CI, so information is required to be added in REDAME specifically under https://github.com/codezonediitj/pydatastructs#guidelines

The following points are to be added,

1. There should be no trailing white spaces in any line.
2. There should only one new line at the end of the each .py file.
3. Any comparison involving True, False or None should be done by reference(is, is not) and not by value(==, !=).

Example of the problem

References/Other comments