Add instructions to readme for intellij / webstorm (#958)

* Add instructions to readme for intellij / webstorm

based on: https://intellij-support.jetbrains.com/hc/en-us/community/posts/360006528060-New-Webstorm-is-missing-debug-integration-with-Typescript

* fix(readme): fix minor issues with intellij readme

* Simplify IntelliJ / Webstorm debug configuration to more closely align with the VSCode example

Co-authored-by: Andrew Bradley <cspotcode@gmail.com>

README.md

@@ -102,6 +102,12 @@ Create a new node.js configuration, add `-r ts-node/register` to node args and m
 
 **Note:** If you are using the `--project <tsconfig.json>` command line argument as per the [Configuration Options](#configuration-options), and want to apply this same behavior when launching in VS Code, add an "env" key into the launch configuration: `"env": { "TS_NODE_PROJECT": "<tsconfig.json>" }`.
 
+### IntelliJ (and WebStorm)
+
+Create a new Node.js configuration and add `-r ts-node/register` to "Node parameters."
+
+**Note:** If you are using the `--project <tsconfig.json>` command line argument as per the [Configuration Options](#configuration-options), and want to apply this same behavior when launching in IntelliJ, specify under "Environment Variables": `TS_NODE_PROJECT=<tsconfig.json>`.
+
 ## How It Works
 
 **TypeScript Node** works by registering the TypeScript compiler for `.tsx?` and `.jsx?` (when `allowJs == true`) extensions. When node.js has an extension registered (via `require.extensions`), it will use the extension internally for module resolution. When an extension is unknown to node.js, it handles the file as `.js` (JavaScript). By default, **TypeScript Node** avoids compiling files in `/node_modules/` for three reasons: