rename ex0 to ex3
add ex4 and ex5
add ex6 Strings And Text
add ex7 More Printing
add ex8 Printing,Printing
add ex9 Printing Printing Printing
add ex10 what was that
add ex11 asking questions
add ex12 libraries
add ex13 parameters unpacking variables
add ex14 prompting and passing
add ex15 reading files
rename ex0
add learn ruby page
add ex16 reading and write file
add ex17 more files
add ex19 names variables code functions
add ex19 functions and variables
add ex20 functions and files
add ex21 functions can return something