Ajout du model expert

Co-authored-by: Kara Diaby <kdiaby.pro@gmail.com>

db/migrate/20210107143316_create_experts.rb

@@ -0,0 +1,7 @@
+class CreateExperts < ActiveRecord::Migration[6.0]
+  def change
+    create_table :experts do |t| # rubocop:disable Style/SymbolProc
+      t.timestamps
+    end
+  end
+end

db/migrate/20210107143938_link_user_and_expert.rb

@@ -0,0 +1,6 @@
+class LinkUserAndExpert < ActiveRecord::Migration[6.0]
+  def change
+    add_reference :users, :expert, index: true
+    add_foreign_key :users, :experts
+  end
+end