added 2.2.0 docs
update the latest version to 2.2.0
update the translation of Home.md. closes #495
update changes and translate added parts. closes #498
copy translations from 2.1.5/manual/Highlights.md. closes #493
copy translations from 2.1.5/manual/Migration.md. closes #496
update changes. closes #499
update changes. this commit closes #500
update changes. closes #506
update changes. closes #507
translate added parts. closes #508
update changes. closes #509
update changes. closes #510
updated changes. closes #511
update changes. closes #534
update changes. closes #535
update changes. closes #536
update changes. closes #537
copy translations of unchanged doc
update changes. closes #538