Update contribution Guidelines to include alphabetical order

contributing.md

@@ -20,7 +20,7 @@ Please ensure your pull request adheres to the following guidelines:
 - Make an individual pull request for each suggestion.
 - Use [title-casing](http://titlecapitalization.com) (AP style).
 - Use the following format: `[List Name](link)`
-- Link additions should be added to the bottom of the relevant category.
+- Link additions should be added in alphabetical order to the relevant category.
 - New categories or improvements to the existing categorization are welcome.
 - Check your spelling and grammar.
 - Make sure your text editor is set to remove trailing whitespace.

readme.md

@@ -193,8 +193,8 @@ The term was coined by Eric Evans in his book of the same title.
 ### PHP
 - [DDD Wish List](https://github.com/franzose/symfony-ddd-wishlist) - A sample application in PHP built with Symfony 3 and Vue.js.
 - [DDD Playground](https://github.com/jorge07/ddd-playground/) - Sample implementation in PHP.
-- [Shop Cart in PHP](https://github.com/simara-svatopluk/cart) - Sample project that demonstrates how simple shop cart can look like. Domain objects,Doctrine integration.,TDD,layers,unit testing
 - [Eric Evans DDD Cargo Sample](https://github.com/codeliner/php-ddd-cargo-sample) - PHP 7 Version of the cargo sample used in Eric Evans DDD book
+- [Shop Cart in PHP](https://github.com/simara-svatopluk/cart) - Sample project that demonstrates how simple shop cart can look like. Domain objects,Doctrine integration.,TDD,layers,unit testing
 
 
 ## Libraries and Frameworks