Readme: Clarify config file names

Closes #465 (tshirt_sizes seem mixed with the default config)

README.md

@@ -40,6 +40,7 @@ To report bugs use [engelsystem/issues](https://github.com/engelsystem/engelsyst
  * Recommended: Directory Listing should be disabled.
  * There must a be MySQL database created with a user who has full rights to that database.
  * If necessary, create a ```config/config.php``` to override values from ```config/config.default.php```.
+   * To remove values from the `available_themes`, `locales` or `tshirt_sizes` lists the config file has to be renamed.
  * To import the database the ```bin/migrate``` script has to be called.
  * In the browser, login with credentials ```admin```:```asdfasdf``` and change the password.
 

config/config.default.php

@@ -56,7 +56,7 @@ return [
         '3' => 'Engelsystem 32c3 (2015)',
         '2' => 'Engelsystem cccamp15',
         '0' => 'Engelsystem light',
-        '1' => 'Engelsystem dark'
+        '1' => 'Engelsystem dark',
     ],
 
     // Rewrite URLs with mod_rewrite
@@ -129,7 +129,7 @@ return [
         'XL-G' => 'XL Girl',
         '2XL'  => '2XL',
         '3XL'  => '3XL',
-        '4XL'  => '4XL'
+        '4XL'  => '4XL',
     ],
 
     // Session config