Change "todos.description" from "string" to "text"

DB field "todos.description" was type string, which
defaults to length 255 in MySQL. Model allows field
to be up to 300 characters, which could cause a DB
error, if user saved a description of between 255
and 300 characters.

db/migrate/20200109231555_change_todo_description.rb

@@ -0,0 +1,12 @@
+class ChangeTodoDescription < ActiveRecord::Migration[5.2]
+  def up 
+    change_table :todos do |t|
+      t.change :description, :text
+    end
+  end
+  def down
+    change_table :todos do |t|
+      t.change :description, :string
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_06_18_202817) do
+ActiveRecord::Schema.define(version: 2020_01_09_231555) do
 
   create_table "attachments", options: "ENGINE=InnoDB DEFAULT CHARSET=utf8", force: :cascade do |t|
     t.integer "todo_id"
@@ -166,7 +166,7 @@ ActiveRecord::Schema.define(version: 2019_06_18_202817) do
   create_table "todos", options: "ENGINE=InnoDB DEFAULT CHARSET=utf8", force: :cascade do |t|
     t.integer "context_id", null: false
     t.integer "project_id"
-    t.string "description", null: false
+    t.text "description", null: false
     t.text "notes", limit: 16777215
     t.datetime "created_at"
     t.datetime "due"