Added new migrations for adding indexes

• Added:
- new migrations for adding indexes

db/migrate/20200707212650_add_index_to_account_flags.rb

@@ -0,0 +1,10 @@
+class AddIndexToAccountFlags < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def change
+    add_index :accounts, :is_pro, algorithm: :concurrently
+    add_index :accounts, :is_verified, algorithm: :concurrently
+    add_index :accounts, :is_donor, algorithm: :concurrently
+    add_index :accounts, :is_investor, algorithm: :concurrently
+  end
+end

db/migrate/20200707212832_add_index_to_account_created_at.rb

@@ -0,0 +1,7 @@
+class AddIndexToAccountCreatedAt < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def change
+    add_index :users, :created_at, algorithm: :concurrently
+  end
+end

db/migrate/20200707212951_add_index_to_media_attachment_type.rb

@@ -0,0 +1,7 @@
+class AddIndexToMediaAttachmentType < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def change
+    add_index :media_attachments, :type, algorithm: :concurrently
+  end
+end