Expand generic types documentation

[pavithraes]

CSP's support for generic types is documented in https://github.com/Point72/csp/wiki/CSP-Node#generic-types, expand this to inlcude:

• How CSP does automatic inference of generic types, which is different from regular python.
• .using -- allows you to force generic type rather than rely on inference. Example usage: csp.const.using(T=[int])([1, 2, 3]) forces the type to a typed list[int], otherwise it would default to just list.