Change settings description (mastodon#10312)

- site_description is no longer visible on front page
- short_description is not fallback to site_description

config/locales/en.yml

@@ -428,13 +428,13 @@ en:
  desc_html: Show a staff badge on a user page
  title: Show staff badge
  site_description:
- desc_html: Introductory paragraph on the frontpage. Describe what makes this Mastodon server special and anything else important. You can use HTML tags, in particular <code>&lt;a&gt;</code> and <code>&lt;em&gt;</code>.
+ desc_html: Introductory paragraph on the API. Describe what makes this Mastodon server special and anything else important. You can use HTML tags, in particular <code>&lt;a&gt;</code> and <code>&lt;em&gt;</code>.
  title: Server description
  site_description_extended:
  desc_html: A good place for your code of conduct, rules, guidelines and other things that set your server apart. You can use HTML tags
  title: Custom extended information
  site_short_description:
- desc_html: Displayed in sidebar and meta tags. Describe what Mastodon is and what makes this server special in a single paragraph. If empty, defaults to server description.
+ desc_html: Displayed in sidebar and meta tags. Describe what Mastodon is and what makes this server special in a single paragraph.
  title: Short server description
  site_terms:
  desc_html: You can write your own privacy policy, terms of service or other legalese. You can use HTML tags