📖 Simplify docking example (#21037)
📖 Simplify docking example (#21037)

TIL (actually yesterday) of `amp-animation.reverse`. This means we can have only one animation and `reverse` it on `undock`.

ABE: ampproject/amp-by-example#1835
cvializ/amphtml,cory-work/amphtml,sharethrough/amphtml,media-net/amphtml,zhangsu/amphtml,adup-tech/amphtml,dotandads/amphtml,jridgewell/amphtml,lannka/amphtml,dotandads/amphtml,dotandads/amphtml,lannka/amphtml,sharethrough/amphtml,erwinmombay/amphtml,jridgewell/amphtml,src-code/amphtml,rsimha-amp/amphtml,jpettitt/amphtml,danielrozenberg/amphtml,zhouyx/amphtml,danielrozenberg/amphtml,prateekbh/amphtml,honeybadgerdontcare/amphtml,alanorozco/amphtml,zhangsu/amphtml,sharethrough/amphtml,smartadserver/amphtml,Gregable/amphtml,voyagegroup/amphtml,zhouyx/amphtml,techhtml/amphtml,src-code/amphtml,jridgewell/amphtml,smartadserver/amphtml,mhc-gh/amphtml,voyagegroup/amphtml,mhc-gh/amphtml,adup-tech/amphtml,src-code/amphtml,Gregable/amphtml,jridgewell/amphtml,voyagegroup/amphtml,voyagegroup/amphtml,erwinmombay/amphtml,alanorozco/amphtml,danielrozenberg/amphtml,nexxtv/amphtml,alanorozco/amphtml,prateekbh/amphtml,mhc-gh/amphtml,erwinmombay/amphtml,honeybadgerdontcare/amphtml,jmadler/amphtml,taboola/amphtml,sebastianbenz/amphtml,Gregable/amphtml,tlong2/amphtml,sebastianbenz/amphtml,rsimha-amp/amphtml,jmadler/amphtml,jpettitt/amphtml,cory-work/amphtml,danielrozenberg/amphtml,taboola/amphtml,cory-work/amphtml,smartadserver/amphtml,cvializ/amphtml,rsimha-amp/amphtml,zhangsu/amphtml,nexxtv/amphtml,tlong2/amphtml,jpettitt/amphtml,alanorozco/amphtml,nexxtv/amphtml,zhangsu/amphtml,danielrozenberg/amphtml,adup-tech/amphtml,smartadserver/amphtml,taboola/amphtml,rsimha-amp/amphtml,cvializ/amphtml,jpettitt/amphtml,zhangsu/amphtml,media-net/amphtml,Gregable/amphtml,alanorozco/amphtml,yandex-pcode/amphtml,erwinmombay/amphtml,voyagegroup/amphtml,techhtml/amphtml,mhc-gh/amphtml,zhouyx/amphtml,sebastianbenz/amphtml,prateekbh/amphtml,ampproject/amphtml,erwinmombay/amphtml,smartadserver/amphtml,zhouyx/amphtml,ampproject/amphtml,prateekbh/amphtml,Gregable/amphtml,sebastianbenz/amphtml,jmadler/amphtml,jridgewell/amphtml,ampproject/amphtml,jridgewell/amphtml,media-net/amphtml,sebastianbenz/amphtml,sebastianbenz/amphtml,Gregable/amphtml,tlong2/amphtml,cvializ/amphtml,jpettitt/amphtml,ampproject/amphtml,cvializ/amphtml,yandex-pcode/amphtml,jpettitt/amphtml,jmadler/amphtml,jpettitt/amphtml,cvializ/amphtml,yandex-pcode/amphtml,media-net/amphtml,ampproject/amphtml,nexxtv/amphtml,media-net/amphtml,taboola/amphtml,zhouyx/amphtml,lannka/amphtml,src-code/amphtml,honeybadgerdontcare/amphtml,alanorozco/amphtml,danielrozenberg/amphtml,zhouyx/amphtml,tlong2/amphtml,rsimha-amp/amphtml,zhouyx/amphtml,cory-work/amphtml,dotandads/amphtml,adup-tech/amphtml,taboola/amphtml,zhangsu/amphtml,nexxtv/amphtml,yandex-pcode/amphtml,prateekbh/amphtml,honeybadgerdontcare/amphtml,techhtml/amphtml,media-net/amphtml,honeybadgerdontcare/amphtml,mhc-gh/amphtml,adup-tech/amphtml,nexxtv/amphtml,src-code/amphtml,ampproject/amphtml,lannka/amphtml,voyagegroup/amphtml,adup-tech/amphtml,mhc-gh/amphtml,tlong2/amphtml,mhc-gh/amphtml,alanorozco/amphtml,erwinmombay/amphtml,sharethrough/amphtml,jmadler/amphtml,honeybadgerdontcare/amphtml,voyagegroup/amphtml,danielrozenberg/amphtml,alanorozco/amphtml,techhtml/amphtml,cory-work/amphtml,ampproject/amphtml,Gregable/amphtml,yandex-pcode/amphtml,tlong2/amphtml,lannka/amphtml,lannka/amphtml,jpettitt/amphtml,honeybadgerdontcare/amphtml,taboola/amphtml,rsimha-amp/amphtml,src-code/amphtml,sharethrough/amphtml,jmadler/amphtml,techhtml/amphtml,danielrozenberg/amphtml,lannka/amphtml,Gregable/amphtml,yandex-pcode/amphtml,rsimha-amp/amphtml,prateekbh/amphtml,ampproject/amphtml,dotandads/amphtml,cory-work/amphtml,mhc-gh/amphtml,smartadserver/amphtml,dotandads/amphtml,yandex-pcode/amphtml,prateekbh/amphtml,taboola/amphtml,sharethrough/amphtml,media-net/amphtml,nexxtv/amphtml,media-net/amphtml,techhtml/amphtml,cory-work/amphtml,jridgewell/amphtml