Adding script for CNV's to master

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "libs/HGVS-syntax-checker"]
+	path = libs/HGVS-syntax-checker
+	url = git@github.com:LOVDnl/HGVS-syntax-checker.git

README.md

@@ -6,6 +6,16 @@ This script will take their export files, normalize and map the variants,
 If previous records are found, they will be updated.
 Records no longer found in LOVD3 will only be marked as removed, if the user requests so.
 
+### Installation
+
+This repository include a "submodule" of the LOVD HGVS library.
+After downloading this repository, you'll need to activate this submodule separately in order to use it.
+Run the following code in the terminal to activate submodules and to download the LOVD HGVS library.
+
+```bash
+git submodule init && git submodule update
+```
+
 ### Grouping the center's raw data files
 
 We used to work with the grouped file generated by the Groningen center.