Fix schema and docs for status_ttl_days and instance

Fixes misspelling and omission of and example in commit
0cfd5b4e89 which added the
status_ttl_property. This was the only place this commit
referred to the property as note_ttl_days.

Partially fixes the omitted schema update of the instance metadata addition
from commit b7e8ce2350. A proper full schema
for nodeinfo is still missing.

docs/docs/development/API/differences_in_mastoapi_responses.md

@@ -113,6 +113,11 @@ Has these additional fields under the `pleroma` object:
 - `notification_settings`: object, can be absent. See `/api/v1/pleroma/notification_settings` for the parameters/keys returned.
 - `favicon`: nullable URL string, Favicon image of the user's instance
 
+Has these additional fields under the `akkoma` object:
+
+- `instance`: nullable object with metadata about the user’s instance
+- `status_ttl_days`: nullable int, default time after which statuses are deleted
+
 ### Source
 
 Has these additional fields under the `pleroma` object:

lib/pleroma/web/api_spec/schemas/account.ex

@@ -112,7 +112,17 @@ defmodule Pleroma.Web.ApiSpec.Schemas.Account do
       akkoma: %Schema{
         type: :object,
         properties: %{
-          note_ttl_days: %Schema{type: :integer}
+          instance: %Schema{
+            type: :object,
+            nullable: true,
+            properties: %{
+              name: %Schema{type: :string},
+              favicon: %Schema{type: :string, format: :uri, nullable: true},
+              # XXX: proper nodeinfo schema
+              nodeinfo: %Schema{type: :object, nullable: true}
+            }
+          },
+          status_ttl_days: %Schema{type: :integer, nullable: true}
         }
       },
       source: %Schema{
@@ -205,6 +215,17 @@ defmodule Pleroma.Web.ApiSpec.Schemas.Account do
           "pleroma-fe" => %{}
         }
       },
+      "akkoma" => %{
+        "instance" => %{
+          "name" => "ihatebeinga.live",
+          "favicon" => "https://ihatebeinga.live/favicon.png",
+          "nodeinfo" =>
+            %{
+              # XXX: nodeinfo schema
+            }
+        },
+        "status_ttl_days" => nil
+      },
       "source" => %{
         "fields" => [],
         "note" => "foobar",