Clarify README and add download instructions

Author: rbaltrusch

README.md

@@ -1,6 +1,6 @@
 # stream.lua
 
-This small, single-file library is an iterator-chaining library implementing common functional programming patterns such as `map`, `filter`, and `reduce`:
+This single-file library is an iterator-chaining library implementing common functional programming patterns such as lazily-computed iterators `map`, `filter`, and `reduce`, a `Stream` class providing iterator-chaining via a fluent interface, and a number of [function utilities](#utilities).
 
 For example, instead of the traditional approach using a for-loop with an if-statement to aggregate transformed data:
 
@@ -47,6 +47,14 @@ This means, that all iterator functions can also be nested (similar to Python),
 
 An added benefit of using the library is that performance seems to be better than the traditional for-loop approach, although this is not the focus or main benefit of this library and as such is not guaranteed.
 
+## Getting started
+
+To use the library, download the [stream.lua](stream.lua) file and include it in your project, then require it in your source code and you are all set up:
+
+```lua
+local fn = require "stream"
+```
+
 ## Documentation
 
 ### Type syntax used and definitions