Integer and boolean type introduction & about

[rajeebkm]

Closes #34, Closes #32

• Integer type introduction and about are added.

[0xNeshi]

Nice work!

Left a couple of nits and a suggestion to add info on boolean operators

[0xNeshi]

Nice. One small nit and we can merge

[0xNeshi]

Corrected one small issue that caused the boolean example not to compile, didn't want to bother you again. Just a note so that you're aware - assert expects its error message to be of type felt252, so you can't use double quotes " ", but single ones ' '. If you wish to use double quotes, i.e. ByteArrays, you should use the assert! macro (note the ! at the end).

So instead of:

// doesn't compile
assert(t == true_expr, "this should be true");

You should write one of the below:

// use felts
assert(t == true_expr, 'this should be true');
// use macro
assert!(t == true_expr, "this should be true");