Add full list of methods in README

Metodology:

```
a = ["address",
 "basic",
 "credit_card",
 "currency",
 "date",
 "email",
 "geo",
 "internet",
 "lorem_ipsum",
 "monetary",
 "name",
 "personal",
 "russian_tax",
 "time"]
def methods(thing); thing.public_methods - thing.parent.public_methods; end
k = a.map { |t| [t, methods(Forgery(t))] }
puts k.map { |a| a.last.map { |c| "    Forgery('#{a.first}').#{c}" } }
```