README.md in snapshot-0.4.7 vs README.md in snapshot-0.4.8

@@ -224,10 +224,16 @@
 
 ```ruby
 ios_version "9.0"
 ```
 
+### Custom Args for the build command
+
+```ruby
+custom_args "GCC_PREPROCESSOR_DEFINITIONS='SCREENSHOTS'"
+```
+
 ### Custom Build Command
 If for some reason, the default build command does not work for your project, you can pass your own build script. The script will be executed **once** before the tests are being run.
 
 **Make sure** you are setting the output path to ```/tmp/snapshot```.
 
@@ -251,11 +257,11 @@
   system("xcrun simctl erase #{udid}")
 end
 
 setup_for_language_change do |lang, device|
   puts "Running #{lang} on #{device}"
-  system("./popuplateDatabase.sh")
+  system("./populateDatabase.sh")
 end
 
 teardown_language do |lang, device|
   puts "Finished with #{lang} on #{device}"
 end
@@ -263,9 +269,11 @@
 teardown_device do |device|
   puts "Cleaning device #{device}"
   system("./cleanup.sh")
 end
 ```
+
+If you want to run a script before each run of the app, it's enough to only implement the `setup_for_language_change` callback.
 
 ### Skip alpha removal from screenshots
 In case you want to skip this process, just add ```skip_alpha_removal``` to your ```Snapfile```.
 
 ### Pass Bundle Identifier