Use DEFAULT_FIELDS_SIZE/MAX_PROFILE_FIELDS value in settings form hint (#1870)

Use `Account::DEFAULT_FIELDS_SIZE` in the hint, which would fallback to
4 if the environment variable isn't set.

app/views/settings/profiles/show.html.haml

@@ -41,7 +41,7 @@
     .fields-row__column.fields-group.fields-row__column-6
       .input.with_block_label
         %label= t('simple_form.labels.defaults.fields')
-        %span.hint= t('simple_form.hints.defaults.fields')
+        %span.hint= t('simple_form.hints.defaults.fields', count: Account::DEFAULT_FIELDS_SIZE)
 
         = f.simple_fields_for :fields do |fields_f|
           .row

config/locales-glitch/simple_form.en.yml

@@ -3,6 +3,7 @@ en:
   simple_form:
     hints:
       defaults:
+        fields: You can have up to %{count} items displayed as a table on your profile
         setting_default_content_type_html: When writing toots, assume they are written in raw HTML, unless specified otherwise
         setting_default_content_type_markdown: When writing toots, assume they are using Markdown for rich text formatting, unless specified otherwise
         setting_default_content_type_plain: When writing toots, assume they are plain text with no special formatting, unless specified otherwise (default Mastodon behavior)