From a shari'a perspective what you quoted is something permissible. But it has no exact backup in the sunnah of the Prophet (pbuh).

Witr is an odd prayer one prays as the last prayer in the night, it might follow a set of two raka'ah prayers (at least this is the view of the majority of scholars) which is either called shaf'a during all months of the year or one may call it tahajjud in Ramadan especially (however some call the last two rak'as shaf'a even in Ramadan).

So usually in Ramadan you pray taraweeh 8, 20 etc raka's in the sum right after 'isha'. And after having a nap you may pray tahajjud as a set of two raka's and end it with witr.

See also:  
https://islam.stackexchange.com/questions/23378/id-like-to-know-about-tahajjud-prayer-in-detail  
https://islam.stackexchange.com/questions/32516/is-sleeping-a-necessary-condition-for-tahajjud-night-prayer  
https://islam.stackexchange.com/questions/25294/is-it-okay-to-perform-tahajjud-after-witir  
https://islam.stackexchange.com/questions/8738/does-taraweeh-replace-tahajjud-prayer-in-the-month-of-ramadan  
https://islam.stackexchange.com/questions/14827/can-one-pray-tahajjud-later-in-the-night-after-they-have-prayed-20-rakah-tarawee  
https://islam.stackexchange.com/questions/33435/can-i-pray-tahajjud-with-only-sura-fariha-and-sura-ikhlas  
https://islam.stackexchange.com/questions/9074/step-by-step-on-how-to-perform-tahajjud-prayer  
https://islam.stackexchange.com/questions/23346/witr-salat-with-isha-and-tahajud  
https://islam.stackexchange.com/questions/38956/reference-of-a-hadith-about-the-night-prayer-of-the-prophet-pbuh