Doc: Update git submodule instructions in readme

README.org

@@ -7,14 +7,13 @@ Inferno game engine project.
 ** Clone
 
 #+BEGIN_SRC sh
-  $ git clone https://gitlab.com/riyyi/inferno
+$ git clone https://github.com/riyyi/inferno
 $ cd inferno
-  $ git submodule init
+$ git submodule update --init --recursive
-  $ git submodule update
 #+END_SRC
 Or
 #+BEGIN_SRC sh
-  $ git clone --recursive https://gitlab.com/riyyi/inferno
+$ git clone --recursive https://github.com/riyyi/inferno
 #+END_SRC
 
 ** Update