add blog post

Author: fractalwrench

README.md

@@ -7,7 +7,7 @@ Converts a JSON string into Kotlin data classes.
 As you've probably guessed by now, this project automatically converts JSON to Kotlin source files. 
 The tool itself is implemented 100% in Kotlin, and makes heavy use of Square's excellent [KotlinPoet](https://github.com/square/kotlinpoet) library.
 
-Read <a href="https://fractalwrench.co.uk/posts/json-2-kotlin/">the blog post</a> which covers how this multi-platform tool was written.
+Read [the blog post](blog/BLOG_POST.md) which covers how this multi-platform tool was written.
 
 View [the source](https://github.com/fractalwrench/json-2-kotlin/tree/master/core/src/main/kotlin/com/fractalwrench/json2kotlin) to suggest improvements.