Added Plugins specific section and updated Contributing doc (#36)

* add specific plugins section now plugin architecture has been released

* updated table of contents

* updated contributing document with further explanations to match the current state of the repo

contributing.md

@@ -3,17 +3,27 @@
 Please be sure to follow the [Tailwind CSS Community Guidelines](https://github.com/tailwindcss/tailwindcss/blob/master/.github/CODE_OF_CONDUCT.md).
 
 1. Make sure you put things in the right category!
-2. Always add your items to the end of a list. To be fair, the order is first-come-first-serve.
-3. If you think something belongs in the wrong category, or think there needs to be a new category, feel free to edit things too.
-
+1. Always add your items to the end of a list. To be fair, the order is first-come-first-serve.
+1. If you think something belongs in the wrong category, or think there needs to be a new category, feel free to edit things too.
+1. Always add the "Add your item" to the end of each list `- [Add Your Item](https://github.com/merchedhq/awesome-tailwindcss/pulls)`
 
 
 ### Projects using Tailwind CSS
 
-Make sure you put things in the right category. There are two main categories:
-- Open Source
-- Apps/Websites
+Make sure you put things in the right category. There are five main categories:
+- Resources
+- Projects Using Tailwind CSS
+  - Open Source
+  - Apps/Websites
+- Components & Libraries
+- Plugins
+- Demos & Samples
 
+### Resources
+
+Official and unofficial resources for getting started with and using the tailwindcss framework.
+
+### Projects Using Tailwind CSS
 #### Open source
 
 Open Source section gives the possibility for developers to contribute and be a part of an opensource project using their knowledge of the Tailwind.
@@ -32,3 +42,15 @@ Apps/Websites gives the opportunity to showcase the awesome things we can build
 You should put your app/website in this category if the following conditions are true:
 - The website is available without errors or ssl certificate problems, and load in a reasonable amount of time.
 - The website is using Tailwind intensively.
+
+### Components & Libraries
+
+Components and libraries that extend the tailwindcss framework.
+
+### Plugins
+
+Tailwindcss plugins that use the [official plugin architecture](https://tailwindcss.com/docs/plugins/) to extend the framework.
+
+### Demos & Samples
+
+Demos, examples and samples of tailwindcss in use.