📝 overworked documentation

Replacing references to std exceptions with user-defined exceptions.
Also changed some examples to the new exceptions.

doc/examples/get_ref.cpp

@@ -19,7 +19,7 @@ int main()
     {
         auto r3 = value.get_ref<json::number_float_t&>();
     }
-    catch (std::domain_error& ex)
+    catch (json::type_error& ex)
     {
         std::cout << ex.what() << '\n';
     }