[com]: add helper_text for resolution and format of poster

com/views.py

@@ -73,6 +73,7 @@ class PosterForm(forms.ModelForm):
             "display_time",
         ]
         widgets = {"screens": forms.CheckboxSelectMultiple}
+        help_texts = {"file": _("Format: 16:9 | Resolution: 1920x1080")}
 
     date_begin = TzAwareDateTimeField(
         label=_("Start date"),