Fix wrong namespace (#415)

Author: GrahamCampbell

UPGRADING.md

@@ -15,7 +15,7 @@ The `getEnvironmentVariableNames` method is no longer available. This is because
 There have been various internal refactorings. Appart from what has already been mentioned, the only other changes likely to affect developers is:
 
 1. The `Dotenv\Environment` namespace has been moved to `Dotenv\Repository`, the `Dotenv\Environment\Adapter\AdapterInterface` interface has been replaced by `Dotenv\Repository\Adapter\ReaderInterface` and `Dotenv\Repository\Adapter\WriterInterface`.
-2. The `Dotenv\Environment\DotenvFactory` has been (roughly) replaced by `Dotenv\Environment\RepositoryBuilder`, and `Dotenv\Environment\FactoryInterface` has been deleted.
+2. The `Dotenv\Environment\DotenvFactory` has been (roughly) replaced by `Dotenv\Repository\RepositoryBuilder`, and `Dotenv\Environment\FactoryInterface` has been deleted.
 3. `Dotenv\Environment\AbstractVariables` has been replaced by `Dotenv\Repository\AbstractRepository`, `Dotenv\Environment\DotenvVariables` has been replaced by `Dotenv\Repository\AdapterRepository`, and `Dotenv\Environment\VariablesInterface` has been replaced by `Dotenv\Repository\RepositoryInterface`.
 4. The `Dotenv\Loader` class has been moved to `Dotenv\Loader\Loader`, and now has a different public interface. It no longer expects any parameters at construction, and implements only the new interface `Dotenv\Loader\LoaderInterface`. Its reponsibility has changed to purely taking raw env file content, and handing it off to the parser, dealing with variable interpolation, and sending off instructions to the repository to set variables. No longer can it be used as a way to read the environment by callers, and nor does it track immutability.
 5. The `Dotenv\Parser` and `Dotenv\Lines` classes have moved to `Dotenv\Loader\Parser` and `Dotenv\Loader\Lines`, respectively. `Dotenv\Loader\Parser::parse` now return has either `null` or `Dotenv\Loader\Value` objects as values, instead of `string`s. This is to support the new variable interpolation and dollar escaping features.