`yii\mongodb\Migration` created
`yii\mongodb\console\controllers\MigrateController` created
Data manipulation methods added to `yii\mongodb\Migration`
mongodb/CHANGELOG updated
Merge pull request #3947 from klimov-paul/mongodb-migration

Enh: MongoDB migration support
Docs about mongodb migration usage adjusted
Typo in guide

Fixed typo in validation guide
Merge pull request #3961 from Theill11/patch-1

Typo in guide
Fixed multiple entries of base migration in history for MongoDB
Merge branch 'master' of github.com:yiisoft/yii2
Fixes #3934: Added attr() method instead prop() to get valid action url.
Merge branch 'master' of https://github.com/yiisoft/yii2