update build docs for PostCSS configuration

www/pages/docs/build.md

@@ -6,8 +6,61 @@ index: 4
 linkheadings: 3
 ---
 
-# Build Configurations
-> ⛔ [_**Coming Soon!**_](https://github.com/ProjectEvergreen/greenwood/issues/426)
+## Build Configurations
+> ⛔ [_**More coming Soon!**_](https://github.com/ProjectEvergreen/greenwood/issues/426)
+
+**Greenwood** offers the ability to extend some of the internal tooling used to better customize the project for those with more advanced use cases than those offered by Greenwood's default.  Greenwood is farily unopinionated in its defaults and aims to provide support for modern web standards that are >= Stage 3 (where applicable).
+
+> _For markdown specific options, please see our docs section on [markdown](/docs/markdown/)._
+
+### PostCSS
+
+To provide addition configurations and optimizations around CSS, user's can add a _postcss.config.js_ file within a project's root directory to take advantage of [**PostCSS**](https://postcss.org/).
+
+For example, if you wanted to write CSS with nested selectors, you would want do the following:
+
+1. Install the relevant PostCSS plugin
+    ```shell
+    $ npm install postcss-nested --save-dev
+    ```
+1. Create a _postcss.config.js_ file and `require` your plugin
+    ```js
+    module.exports = {
+      plugins: [
+        require('postcss-nested')
+      ]
+    };
+    ```
+1. Now you can write nested CSS!
+    ```css
+    :host {
+      & .card {
+        padding: 2.5rem;
+        position: relative;
+        display: flex;
+        flex-direction: column;
+        min-width: 0;
+        word-wrap: break-word;
+        background-color: #fff;
+        background-clip: initial;
+        text-align: center;
+
+        & .body {
+          padding:10px;
+        }
+
+        @media(max-width:768px) {
+          padding:0;
+        }
+      }
+    }
+    ```
+
+> _For reference, [this is the default _postcss.config.js_](https://github.com/ProjectEvergreen/greenwood/blob/master/packages/cli/src/config/postcss.config.js) being provided by Greenwood._
+
+<!--
+> Note: [.browserslistrc](#browserslist) is used by postcss and is also needed to be overwritten. You can override that in that same directory or you may also configure postcss-preset-env to use default `.browserslistrc` path via environement variable to: `./node_modules/@greenwood/cli/src/config/.browserslistrc`.  See [postcss-preset-env docs](https://www.npmjs.com/package/postcss-preset-env#browsers) for further information. [Ejecting configuration](#eject-configuration) is one way in which you can easily override both with no extra configuraiton.
+-->
 
 <!-- 
 A number of [core build configuration files](https://github.com/ProjectEvergreen/greenwood/tree/master/packages/cli/src/config) can be overridden by creating each file within the root path of your project. You can also automate this task in a single command [see eject configurations](#eject-configurations).
@@ -36,11 +89,6 @@ By default, [this is the postcss.config.js](https://github.com/ProjectEvergreen/
 
 > Note: [.browserslistrc](#browserslist) is used by postcss and is also needed to be overwritten. You can override that in that same directory or you may also configure postcss-preset-env to use default `.browserslistrc` path via environement variable to: `./node_modules/@greenwood/cli/src/config/.browserslistrc`.  See [postcss-preset-env docs](https://www.npmjs.com/package/postcss-preset-env#browsers) for further information. [Ejecting configuration](#eject-configuration) is one way in which you can easily override both with no extra configuraiton.
 
-### Webpack
-
-The webpack config for production(`webpack.config.prod.js`) and development(`webpack.config.develop.js`) can be overridden by providing your own custom configuration within your project's directory.  You can eject the default core configurations into your project using greenwood cli [eject](#eject-configurations) command and then edit them after, which is the simplest and recommended method for modifying webpack config.  If you wish to revert back to the default provided configuration, simply delete these 2 files from your project's root directory. 
-A number of core build configuration files can be overridden by creating each file within the root path of your project.
-
 ### Eject Configurations
 
 From greenwood CLI you can eject [core configuration files(webpack, postcss, babel, browserslistrc)](https://github.com/ProjectEvergreen/greenwood/tree/master/packages/cli/src/config) into your project's working directory which will make it easier to add your own customizations.  To do so, add the following to your package.json `scripts` object: