Add documentation for flutter usage (#67)

* Add documentation for flutter usage

* Fix typos issues

* Fix more typos

README.md

@@ -85,7 +85,7 @@ dotenv["MY_ENV_VAR1"]
 
  <img src="assets/android-dotenv.png" width="350">
 
-- Configure dotenv to search `/assets` for a file with name `env`
+- Configure dotenv to search `./assets` for a file with name `env`
 
  ```kotlin
  val dotenv = dotenv {
@@ -95,14 +95,29 @@ dotenv["MY_ENV_VAR1"]
  dotenv["MY_ENV_VAR1"]
  ```
 
-**Note:** The above configuration is required because dot files in `/assets` do not appear to resolve on Android. *(Seeking recommendations from the Android community on how `dotenv-kotlin` configuration should work in order to provide the best experience for Android developers)*
+**Note:** The above configuration is required because dot files in `./assets` do not appear to resolve on Android. *(Seeking recommendations from the Android community on how `dotenv-kotlin` configuration should work in order to provide the best experience for Android developers)*
 
 Alternatively, if you are using Provider `android.resource` you may specify
 
 ```
  directory = "android.resource://com.example.dimascio.myapp/raw"
 ```
 
+## Flutter Usage
+Advices to use the package in the native Android layer prior to the flutter initialization.
+
+* Create an assets folder inside `/android/app/src/main/`
+* Add `env` (not dot) file to the assets folder.
+* Configure dotenv to search ./assets for a file with name `env`.
+```kotlin
+ val dotenv = dotenv {
+ directory = "./assets"
+ filename = "env" // instead of '.env', use 'env'
+ }
+ dotenv["MY_ENV_VAR1"] ?: ""
+```
+* Is a good practice to ignore the env file from the repository. For this purpose you can use the `.gitignore` inside the android folder
+
 ## Advanced Usage
 
 ### Configure