Update Readme

[abrahamcuenca]

Add assets/.env in examples

[abrahamcuenca]

@java-james I am new to flutter development and I spent about an hour trying to debug my application thinking something was wrong. I followed the documentation but after carefully stepping through everything for the n-th time I noticed I had followed the documentation faithfully only to discover I had to load the file from the path described a few steps before DotEnv().load('assets/.env')

I think updating this would help future users (and new flutter users) use this wonderful package without confusion.

[saitho]

I'm also new to Flutter and startet a couple days ago, but I have to say that the documentation is correct.

The file does not go into the ./assets folder but in the project root. It only says that you have to add that file to the "assets" array of pubspec.yaml.

[abrahamcuenca]

Ah ok - All along I may have misread it then. Thanks Saitho!