Update README [skip ci]

Author: pkrll

README.md

@@ -2,56 +2,129 @@
 [![codecov](https://codecov.io/gh/pkrll/Hazel/branch/master/graph/badge.svg)](https://codecov.io/gh/pkrll/Hazel)
 <img src=".assets/hazel.png" data-canonical-src=".assets/hazel.png" />
 
-**Hazel** is a command line tool that helps you start a new project faster -- by setting up the structure and generating common files.
+``Hazel`` is a **cross-platform project scaffolding tool** that makes it easier to start new projects. The CLI application **generates the directory structure and boilerplate code** for your projects, based on **predefined templates**, and can **easily** be **customized and extended**.
 
-- [x] Support for C projects
-- [ ] Support for even more languages
-- [ ] Generate git repository
+- [x] Generate project structure based on templates
+- [x] Support for macOS
+- [ ] Support for Linux
 
-### Installation
+## Table of contents
 
-Clone this repository, and run ``make install``:
+* [Usage](#usage)
+	* [Customization](#customization)
+		* [Example](#example)
+		* [Placeholders](#placeholders)
+		* [Command-line options](#command-line-options)
+* [Installation](#installation)
+	* [Prerequisites](#prerequisites)
+* [Acknowledgements](#acknowledgements)
+
+## Usage
+
+Run ``Hazel`` inside the root folder for your project with the ``init`` command, along with the ``--type``, or ``-t``, flag to generate the directory structure and the files:
 
 ```bash
-$ git clone https://github.com/pkrll/Hazel
-$ cd Hazel
-$ make install
+$ mkdir SomeApp && cd SomeApp
+$ hazel init --type c
+
+Created obj
+Created bin
+Created tests
+Created src
+Created obj/.gitkeep
+Created bin/.gitkeep
+Created Makefile
+Created tests/SomeApp_test.c
+Created src/SomeApp.c
+Created .editorconfig
 ```
 
-This will install **Hazel** in ``/usr/local/bin``, along with its templates files in ``~/.hazel``.
+<img src=".assets/hazel.gif">
+
+### Customization
+
+``Hazel`` generates new projects based on predefined templates, placed in ``~/.hazel/templates``. You can add your own templates by simply creating a desired directory structure, along with the files you want to be automatically generated, in a subdirectory to ``~/.hazel/templates``.
 
-### Usage
+The name of the subdirectory will serve as the name of the project.
 
-Run **Hazel** inside the root folder for your project to generate the directory structure:
+#### Example
+
+Let's create a (**very**) simple template for Swift projects.
 
 ```bash
-$ mkdir SomeProject
-$ hazel --type c
+$ cd ~/.hazel/templates
 
-Created bin
-Created obj
+$ mkdir Swift && cd Swift
+$ touch README.md
+$ mkdir src
+$ touch src/__PROJECTNAME__.swift
+
+# __PROJECTNAME__ is a placeholder that will be
+# replaced by the project name when running hazel
+
+$ tree
+.
+├── README.md
+├── src
+    └── __PROJECTNAME__.swift
+```
+
+To generate new projects based on the above template, we can now initiate a new project of type ``swift``:
+
+```bash
+$ mkdir AwesomeApp && cd AwesomeApp
+$ hazel init --type swift
+
+Created README.md
 Created src
-Created tests
-Created Makefile
+Created src/AwesomeApp.c
 Created .editorconfig
 ```
 
-##### Command line options
+#### Placeholders
+
+When generating new projects, ``Hazel`` will replace all occurrences of placeholder variables in the template with appropriate values. This includes both file and directory names as well as the actual contents of the template files.
+
+As of now, support exists for the following placeholders:
+
+| Placeholder | Description |
+| :------------- | :------------- |
+| ``__PROJECTNAME__`` | All occurrences of this placeholder will be replaced with the name of the project.       |
+| More to come | ... |
+
+#### Commandline options
 
 ```bash
-Usage: hazel [options]
-  -t, --type:
-      Choose language for project: [c|c++|swift|java|erlang]
-  --no-makefile:
-      Do not generate Makefile
-  --no-config:
-      Do not generate .editorconfig
-  -h, --help:
-      Print help message and exit
-  -v, --version:
-      Print version information and exit
+Usage: hazel [command] [argument]
+
+Commands:
+  init           Initiate a new project
+
+Options:
+  -h, --help     Print help message and exit
+  -v, --version  Print version information and exit
+
 ```
 
-# Author
+## Installation
+
+``Hazel`` has only been tested on macOS High Sierra (10.13), so far, and is only available for download through Github.
+
+**Prerequisites**:
+
+* Swift 4.0
+* Git
+
+Clone this repository, and run ``make install``:
+
+```bash
+$ git clone https://github.com/pkrll/Hazel
+$ cd Hazel
+$ make install
+```
+
+This will install ``Hazel`` in ``/usr/local/bin``, along with its templates files in ``~/.hazel``.
+
+## Acknowledgements
 
-**Hazel** was created by Ardalan Samimi. The hazel nut icon was designed by [Flaticon](https://www.flaticon.com).
+``Hazel`` was created by [Ardalan Samimi](https://github.com/pkrll). This project is licensed under the terms of the MIT license. The hazel nut icon was designed by [Flaticon](https://www.flaticon.com).