Updating the help_text for the SSH form

I updated the SSH form in order to create the `help_text` argument in
the form class and call it directly in the template.

Signed-off-by: Matthieu Berjon <matthieu.berjon@inria.fr>

django/allgo/main/forms.py

@@ -44,7 +44,8 @@ class SSHForm(forms.ModelForm):
     sshkey = forms.CharField(
             label="SSH Key",
             label_suffix='',
-            widget=forms.Textarea)
+            widget=forms.Textarea,
+            help_text=mark_safe('Before you can add an SSH key you need to <a href="https://gitlab.inria.fr/help/ssh/README#generating-a-new-ssh-key-pair">generate one</a> or use an <a href="https://gitlab.inria.fr/help/ssh/README#locating-an-existing-ssh-key-pair">existing key.</a>'),)
 
     class Meta:
         model = AllgoUser

django/allgo/templates/user_ssh_add.html

@@ -16,12 +16,7 @@
 
           <div class="form-group">
           {{ form.sshkey.label_tag }}
-          <small class="form-text text-muted">
-            Before you can add an SSH key you need to
-            <a href="https://gitlab.inria.fr/help/ssh/README#generating-a-new-ssh-key-pair">generate one</a>
-            or use an
-            <a href="https://gitlab.inria.fr/help/ssh/README#locating-an-existing-ssh-key-pair">existing key.</a>
-          </small>
+          <small class="form-text text-muted">{{ form.sshkey.help_text }}</small>
           {{ form.sshkey | attr:"placeholder:Example ssh-rsa ...." | add_class:"form-control" }}
           </div>