Update reference_documents.md

Author: bboyho

docs/reference_documents.md

@@ -2,5 +2,9 @@
 
 This is a list of technical documents pertaining to each RTK Everywhere based product.
 
-* [RTK Torch Datasheets](https://docs.sparkfun.com/SparkFun_RTK_Torch/reference_documents/)
-* [RTK Torch Hookup Guide](https://docs.sparkfun.com/SparkFun_RTK_Torch/)
+* RTK Torch
+    * [Datasheets](https://docs.sparkfun.com/SparkFun_RTK_Torch/reference_documents/)
+    * [Hookup Guide](https://docs.sparkfun.com/SparkFun_RTK_Torch/)
+* RTK EVK
+    * [Datasheets](https://docs.sparkfun.com/SparkFun_RTK_EVK/resources/)
+    * [Hookup Guide](https://docs.sparkfun.com/SparkFun_RTK_EVK/)