Add documentation

[AntonisZks]

Add documentation to the code and create a README.md file for the whole project. For the documentation I suggest we use java DocStrings. A usage example is the following:

/**
 * @brief Adds two numbers
 * 
 * @param num1 the first number
 * @param num2 the second number
 * 
 * @return the sum of num1 and num2
 */
int add numbers(int num1, int num2) {
  return num1 + num2;
}

• [x] Add documentation to the code.
• [x] Create README.md for the project.

[StavrosJKw]

I have started documenting our project