chore: update readme

Readme.md

@@ -4,6 +4,45 @@ A simple library to take die rolling shorthand and return the result
 
 ## Installing
 
-`npm install @evilmonkeyinc/die-roller`
+This library ahs been published to NPM and can be installed with npm or yarn
 
-`yarn add @evilmonkeyinc/die-roller`
+```npm
+npm install @evilmonkeyinc/die-roller
+````
+
+```yarn
+yarn add @evilmonkeyinc/die-roller
+```
+
+The library will be compatible with both javascript and typescript
+
+## Usage
+
+```
+import { parse } from '@evilmonkeyinc/die-roller'
+
+...
+
+const parsedExpression = parse('4d6k3')
+console.log(parsedExpression.result);
+// will return a number between 3 and 18
+```
+
+The `parse` function will take a die expression shorthand and evaluate it and return the result.
+
+The expression should be in the format `{number of die}d{size of die}{options}`
+
+The options are used to perform simple actions on the die results before giving back the result, such as `2d20k1` which would return the higher of two d20 rolls or `4d6k3` which would return the result of the best three d6 rolls out of 4.
+
+| Option     | Description                                   |
+| ---------- | --------------------------------------------- |
+| k{number}  | Keep only the highest {number} of die results |
+| kh{number} | Keep only the highest {number} of die results |
+| kl{number} | Keep only the lowest {number} of die results  |
+| d{number}  | Drop the lowest {number} of die results       |
+| dl{number} | Drop the lowest {number} of die results       |
+| dh{number} | Drop the highest {number} of die results      |
+
+You can also chain expressions, or simply add or subtract whole numbers for the result by appending a `+` or `-` to an expression if you need to include modifiers to your results.
+
+`1d20+2+3` for your Palidin attacking with their Longsword, with their 2 in proficiency and 3 strength. You hit, and decide to SMITE the enemy, you could then roll `1d8+3+2d8` for damage, `1d8+3` for the weapon and `2d8` for a Divine Smite at 1st level