Add Nim Basics Free Ebook (#3421)

* Add Nim Basics Free Ebook

* add spaces to satisfy linter

free-programming-books.md

@@ -148,6 +148,7 @@
 * [MySQL](#mysql)
 * [Neo4J](#neo4j)
 * [.NET Framework](#net-framework)
+* [Nim](#nim)
 * [NoSQL](#nosql)
 * [Oberon](#oberon)
 * [Objective-C](#objective-c)
@@ -1891,6 +1892,11 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Visual Studio .NET Tips and Tricks](http://www.infoq.com/minibooks/vsnettt) (VS 2003-2005 only)
 
 
+### Nim
+
+* [Nim Basics](https://narimiran.github.io/nim-basics/)
+
+
 ### NoSQL
 
 * [CouchDB: The Definitive Guide](http://guide.couchdb.org)