Documentation: improve image fetching docs
Documentation: improve image fetching docs

After Rob Szumski's feedback on #1560.

yifan-gu/rocket,ybubnov/rkt,kbrwn/rkt,lucasallan/rkt,matthaias/rkt,liugenping/rkt,endocode/rkt,liugenping/rkt,akshaykarle/rkt,il9ue/rkt,jjlakis/rkt,achanda/rkt,matthaias/rkt,yifan-gu/rkt,achanda/rkt,akshaykarle/rkt,alban/rkt,liugenping/rkt,tmrts/rkt,ybubnov/rkt,shobhit85/rkt,markllama/rkt,yifan-gu/rocket,shobhit85/rkt,joshix/rkt,shobhit85/rkt,kinvolk/rkt,Wilybald/rkt,dgonyeo/rkt,alban/rkt,lucasallan/rkt,kinvolk/rkt,intelsdi-x/rkt,endocode/rkt,s-urbaniak/rkt,coreos/rkt,dgonyeo/rkt,rkt/rkt,kinvolk/rkt,Wilybald/rkt,jjlakis/rkt,sinfomicien/rkt,squeed/rkt,Shashwatsh/rkt,akshaykarle/rkt,jasonchaffee/rkt,lucasallan/rkt,adfernandes/rkt,monstermunchkin/rkt,tmrts/rkt,blixtra/rkt,joshix/rkt,kbrwn/rkt,monstermunchkin/rkt,euank/rkt,mike1729/rkt,joshix/rkt,linki/rkt,linki/rkt,Wilybald/rkt,nhlfr/rkt,il9ue/rkt,blixtra/rkt,sgotti/rkt,jonboulle/rkt,blixtra/rkt,coreos/rkt,intelsdi-x/rkt,krnowak/rkt,jonboulle/rkt,jakon89/rkt,achanda/rkt,linki/rkt,sgotti/rkt,coreos/rkt,jzelinskie/rkt,jakon89/rkt,Shashwatsh/rkt,sinfomicien/rkt,alban/rkt,matthaias/rkt,kinvolk/rkt,monstermunchkin/rkt,euank/rkt,jzelinskie/rkt,s-urbaniak/rkt,ybubnov/rkt,rkt/rkt,cab105/rkt,sgotti/rkt,jasonchaffee/rkt,markllama/rkt,adfernandes/rkt,tmrts/rkt,rkt/rkt,sstabellini/rkt,jasonchaffee/rkt,nhlfr/rkt,joshix/rkt,sstabellini/rkt,rkt/rkt,euank/rkt,mike1729/rkt,jzelinskie/rkt,kbrwn/rkt,Wilybald/rkt,s-urbaniak/rkt,dgonyeo/rkt,sstabellini/rkt,mike1729/rkt,cab105/rkt,krnowak/rkt,adfernandes/rkt,intelsdi-x/rkt,Shashwatsh/rkt,yifan-gu/rkt,il9ue/rkt,krnowak/rkt,yifan-gu/rocket,jonboulle/rkt,yifan-gu/rkt,squeed/rkt,sinfomicien/rkt,jjlakis/rkt,jakon89/rkt,squeed/rkt,cab105/rkt,lucasallan/rkt,markllama/rkt,nhlfr/rkt,endocode/rkt