add double-click tip to availability form

fixes #81

AKModel/availability/forms.py

@@ -19,7 +19,7 @@ class AvailabilitiesFormMixin(forms.Form):
     availabilities = forms.CharField(
         label=_('Availability'),
         help_text=_(
-            'Please click and drag to mark the availability during the event.'
+            'Click and drag to mark the availability during the event, double-click to delete.'  # Adapted help text
         ),
         widget=forms.TextInput(attrs={'class': 'availabilities-editor-data'}),
         required=False,

AKModel/locale/de_DE/LC_MESSAGES/django.po

@@ -37,10 +37,10 @@ msgid "Availability"
 msgstr "Verfügbarkeit"
 
 #: AKModel/availability/forms.py:22
-msgid "Please click and drag to mark the availability during the event."
+msgid "Click and drag to mark the availability during the event, double-click to delete."
 msgstr ""
-"Bitte klicken und ziehen um die Verfügbarkeiten während des Events zu "
-"markieren."
+"Klicken und ziehen um die Verfügbarkeiten während des Events zu "
+"markieren. Doppelt klicken um Einträge zu löschen."
 
 #: AKModel/availability/forms.py:86
 msgid "The submitted availability does not comply with the required format."