ADD project detail api

db/migrate/20201004070431_create_project_details.rb

@@ -0,0 +1,12 @@
+class CreateProjectDetails < ActiveRecord::Migration[5.2]
+  def change
+    create_table :project_details do |t|
+      t.integer :project_id
+      t.longtext :content
+
+      t.timestamps
+    end
+
+    add_index :project_details, :project_id
+  end
+end