docs(): documentation usage + example screenshots

Author: matejchalk

README.md

@@ -1,14 +1,71 @@
 # Import Graph Visualizer
 
-_TODO: description_
+**Import Graph Visualizer is a development tool for filtering and visualizing import paths within a JavaScript/TypeScript application.**
+
+## Motivation
+
+Although there are already excellent tools out there for visualizing imports between Node.js modules (e.g. [Dependency Cruiser](https://github.com/sverweij/dependency-cruiser), which is actually used by this tool under the hood), for large apps these graphs may be too large to comprehend.
+This is why Import Graph Visualizer allows filtering import paths by source and target modules, allowing you to zoom in to a limited subsection of your app, which will likely be easier to analyze than the entire app as a whole.
+
+## Examples
+
+Screenshot of Import Graph Visualizer for this repository:
+
+![self example](./docs/images/self-example.png)
+
+For an Ionic/Angular starter project:
+
+![Ionic/Angular example](./docs/images/ionic-angular-example.png)
+
+For `vis-network` repo:
+
+![vis-network example](./docs/images/vis-network-example.png)
 
 ## Setup
 
-_TODO_
+To install as a development dependency in your Node project:
+
+```sh
+npm install --save-dev import-graph-visualizer
+```
+
+Alternatively, to install as a global dependency (prefix with `sudo` on Unix systems):
+
+```sh
+npm install --global import-graph-visualizer
+```
 
 ## Usage
 
-_TODO_
+To run this tool, you must supply at least one entry point for your application (e.g. `src/index.js`):
+
+```sh
+npx import-graph-visualizer --entry-points path/to/entry/module
+```
+
+For Typescript projects that use path aliases, make sure to also specify your `tsconfig.json` path:
+
+```sh
+npx import-graph-visualizer --entry-points path/to/entry/module --ts-config path/to/tsconfig
+```
+
+For greater convenience, you may wish to add a script to your `package.json`:
+
+```json
+{
+  // ...
+  "scripts": {
+    // ...
+    "import-graph-visualizer": "import-graph-visualizer --entry-points path/to/entry/module ..."
+  }
+}
+```
+
+Then you may run it as:
+
+```sh
+npm run import-graph-visualizer
+```
 
 ## Development