fix link and add doc

frozen/gigasom.md

@@ -20,9 +20,14 @@ and [FR-FCM-ZYX9](http://flowrepository.org/id/FR-FCM-ZYX9).
 {% endrblock %}
 
 {% rblock source code %}
-**GigaSOM.jl** source code is hosted on [Github](https://git-r3lab.uni.lu/LCSB-BioCore/GigaSOM.jl).
+**GigaSOM.jl** source code is hosted on [Github](https://github.com/LCSB-BioCore/GigaSOM.jl).
 **GigaScatter.jl**, used for dataset rasterization, is also hosted on [Github](https://github.com/LCSB-BioCore/GigaScatter.jl).
 
 {% endrblock %}
 
+{% rblock documentation | fas fa-book %}
+The documentation of **GigaSOM.jl** is available [here](https://git.io/GigaSOM.jl).
+
+{% endrblock %}
+
 {% endrgridblock %}
\ No newline at end of file