Improve comments webhooks description

Webhooks for comments (notes) are not only triggered in issues
but also in merge requests.

app/views/shared/web_hooks/_form.html.haml

@@ -33,7 +33,7 @@
       = form.label :note_events, class: 'list-label form-check-label gl-ml-1' do
         %strong= s_('Webhooks|Comments')
       %p.text-muted.gl-ml-1
-        = s_('Webhooks|A comment is added to an issue.')
+        = s_('Webhooks|A comment is added to an issue or merge request.')
     %li
       = form.check_box :confidential_note_events, class: 'form-check-input'
       = form.label :confidential_note_events, class: 'list-label form-check-label gl-ml-1' do

locale/gitlab.pot

@@ -42003,7 +42003,7 @@ msgstr ""
 msgid "Webhooks|A comment is added to a confidential issue."
 msgstr ""
 
-msgid "Webhooks|A comment is added to an issue."
+msgid "Webhooks|A comment is added to an issue or merge request."
 msgstr ""
 
 msgid "Webhooks|A confidential issue is created, updated, closed, or reopened."