Redux Observable module needs documentation warning

[lagoasoft-lucasschmidt]

Guys ... we need to let users know that it is used the toString method in the Epic function as key in order to determine if an epic will be added or not.

If you use an epic generator function, dynamic modules wont add all the epics, only a single one of them, since their toString methods return the same value.

I dont think any internal changes should be done, just a warning in the docs would be enough for most users.