Add development section

* I cretaed a folder 'development'
* I split up the file dev.md into three parts and moved it to this folder
  * index.md
  * authentication_authorization.md
  * mrf.md
* I also moved ap_extensions.md
* I created a new file setting_up_pleroma_dev.md

priv/repo/optional_migrations/rum_indexing/20190510135645_add_fts_index_to_objects_two.exs

@@ -3,7 +3,14 @@ defmodule Pleroma.Repo.Migrations.AddFtsIndexToObjectsTwo do
 
   def up do
     execute("create extension if not exists rum")
-    drop_if_exists index(:objects, ["(to_tsvector('english', data->>'content'))"], using: :gin, name: :objects_fts)
+
+    drop_if_exists(
+      index(:objects, ["(to_tsvector('english', data->>'content'))"],
+        using: :gin,
+        name: :objects_fts
+      )
+    )
+
     alter table(:objects) do
       add(:fts_content, :tsvector)
     end
@@ -14,7 +21,10 @@ defmodule Pleroma.Repo.Migrations.AddFtsIndexToObjectsTwo do
     return new;
     end
     $$ LANGUAGE plpgsql")
-    execute("create index if not exists objects_fts on objects using RUM (fts_content rum_tsvector_addon_ops, inserted_at) with (attach = 'inserted_at', to = 'fts_content');")
+
+    execute(
+      "create index if not exists objects_fts on objects using RUM (fts_content rum_tsvector_addon_ops, inserted_at) with (attach = 'inserted_at', to = 'fts_content');"
+    )
 
     execute("CREATE TRIGGER tsvectorupdate BEFORE INSERT OR UPDATE ON objects
     FOR EACH ROW EXECUTE PROCEDURE objects_fts_update()")
@@ -23,12 +33,19 @@ defmodule Pleroma.Repo.Migrations.AddFtsIndexToObjectsTwo do
   end
 
   def down do
-    execute "drop index if exists objects_fts"
-    execute "drop trigger if exists tsvectorupdate on objects"
-    execute "drop function if exists objects_fts_update()"
+    execute("drop index if exists objects_fts")
+    execute("drop trigger if exists tsvectorupdate on objects")
+    execute("drop function if exists objects_fts_update()")
+
     alter table(:objects) do
       remove(:fts_content, :tsvector)
     end
-    create_if_not_exists index(:objects, ["(to_tsvector('english', data->>'content'))"], using: :gin, name: :objects_fts)
+
+    create_if_not_exists(
+      index(:objects, ["(to_tsvector('english', data->>'content'))"],
+        using: :gin,
+        name: :objects_fts
+      )
+    )
   end
 end