Fix protocol usage for cloning GitHub's repository

Output on my machine:

$ git clone git://github.com/lisa-lab/DeepLearningTutorials.git
Cloning into 'DeepLearningTutorials'...
fatal: unable to connect to github.com:
github.com[0: 192.30.252.128]: errno=Connection refused

However:

$ git clone https://github.com/lisa-lab/DeepLearningTutorials.git
Cloning into 'DeepLearningTutorials'...
remote: Counting objects: 3652, done.
remote: Total 3652 (delta 0), reused 0 (delta 0), pack-reused 3652
Receiving objects: 100% (3652/3652), 7.80 MiB | 1.77 MiB/s, done.
Resolving deltas: 100% (2161/2161), done.
Checking connectivity... done.

I just used the GitHub's clone URL (default protocol is https)

Author: gut

doc/gettingstarted.txt

@@ -20,7 +20,7 @@ Download
 
 On each learning algorithm page, you will be able to download the corresponding files. If you want to download all of them at the same time, you can clone the git repository of the tutorial::
 
-    git clone git://github.com/lisa-lab/DeepLearningTutorials.git
+    git clone https://github.com/lisa-lab/DeepLearningTutorials.git
 
 
 .. _datasets: