README: Start "Usage" section

README.md

@@ -4,18 +4,7 @@ Extremely lightweight, zero dependency variable checks missing in nodeJS but com
 is.nullOrEmpty(input: any): boolean
 is.string(input: any): boolean;
 ```
-Install it from [NPM](https://www.npmjs.com/package/@kj4ezj/is) with your preferred package manager...
-```bash
-bun add @kj4ezj/is
-cnpm install @kj4ezj/is
-npm install @kj4ezj/is
-pnpm add @kj4ezj/is
-yarn add @kj4ezj/is
-```
-...then import it into your source code.
-```js
-const is = require('@kj4ezj/is');
-```
+Install `@kj4ezj/is` from [NPM](https://www.npmjs.com/package/@kj4ezj/is) with your preferred package manager!
 
 <!-- contents box begin -->
 <table>
@@ -30,6 +19,7 @@ const is = require('@kj4ezj/is');
 <!-- contents markdown begin -->
 
 1. [Background](#background)
+1. [Usage](#usage)
 1. [Development](#development)
     1. [Prerequisites](#prerequisites)
     1. [Initialization](#initialization)
@@ -52,6 +42,26 @@ In the old days™, nodeJS lacked most utilities developers take for granted in
 
 The `is.js` library provides the most fundamental utilities remaining absent in modern `node` that I expect to have in any language, and nothing more. At the time of writing, `is.js` weighs in at just _461 bytes_, five orders of magnitude smaller than `lodash`!
 
+## Usage
+Install `@kj4ezj/is` from [NPM](https://www.npmjs.com/package/@kj4ezj/is) with your preferred package manager...
+```bash
+bun add @kj4ezj/is
+cnpm install @kj4ezj/is
+npm install @kj4ezj/is
+pnpm add @kj4ezj/is
+yarn add @kj4ezj/is
+```
+...then import it into your source code.
+```js
+const is = require('@kj4ezj/is');
+```
+Two utilities are provided.
+```ts
+is.nullOrEmpty(input: any): boolean
+is.string(input: any): boolean;
+```
+These are documented in the sections below, but the [test cases](./is.test.js) written against expectations should be considered authoritative.
+
 ## Development
 Start here to contribute to this repo.