Rollup merge of #21450 - alfie:book2, r=steveklabnik
Rollup merge of #21450 - alfie:book2, r=steveklabnik

Compiling won't produce an executable just yet because (as stated in the next
paragraph) there are errors. By removing this sentance, the reader won't get
confused when they expect a successful compile i.e. if they don't read ahead one
paragraph, they are going to be checking their code and wondering why it's not
compiling.

aneeshusa/rust,seanrivera/rust,rohitjoshi/rust,dinfuehr/rust,zachwick/rust,rprichard/rust,ruud-v-a/rust,sae-bom/rust,mvdnes/rust,aidancully/rust,gifnksm/rust,XMPPwocky/rust,untitaker/rust,zaeleus/rust,aidancully/rust,zubron/rust,cllns/rust,cllns/rust,pshc/rust,avdi/rust,miniupnp/rust,rprichard/rust,victorvde/rust,l0kod/rust,nwin/rust,mvdnes/rust,zubron/rust,aepsil0n/rust,kwantam/rust,aneeshusa/rust,seanrivera/rust,carols10cents/rust,ebfull/rust,gifnksm/rust,gifnksm/rust,miniupnp/rust,aneeshusa/rust,GBGamer/rust,seanrivera/rust,l0kod/rust,pshc/rust,mdinger/rust,richo/rust,bombless/rust,andars/rust,hauleth/rust,jashank/rust,rprichard/rust,mihneadb/rust,richo/rust,mahkoh/rust,rprichard/rust,andars/rust,dwillmer/rust,richo/rust,dwillmer/rust,victorvde/rust,bombless/rust,GBGamer/rust,dinfuehr/rust,mdinger/rust,ejjeong/rust,zaeleus/rust,XMPPwocky/rust,KokaKiwi/rust,TheNeikos/rust,bombless/rust,krzysz00/rust,l0kod/rust,jashank/rust,reem/rust,mihneadb/rust,XMPPwocky/rust,reem/rust,dinfuehr/rust,krzysz00/rust,GBGamer/rust,ruud-v-a/rust,ebfull/rust,reem/rust,jroesch/rust,cllns/rust,jashank/rust,zubron/rust,pshc/rust,philyoon/rust,graydon/rust,miniupnp/rust,mdinger/rust,KokaKiwi/rust,robertg/rust,zachwick/rust,vhbit/rust,AerialX/rust,rohitjoshi/rust,zubron/rust,seanrivera/rust,jroesch/rust,carols10cents/rust,rohitjoshi/rust,graydon/rust,mahkoh/rust,robertg/rust,zaeleus/rust,vhbit/rust,zachwick/rust,dinfuehr/rust,aneeshusa/rust,omasanori/rust,bombless/rust,XMPPwocky/rust,AerialX/rust-rt-minimal,avdi/rust,GBGamer/rust,richo/rust,zubron/rust,mdinger/rust,KokaKiwi/rust,kwantam/rust,zaeleus/rust,zachwick/rust,rprichard/rust,jroesch/rust,dwillmer/rust,jashank/rust,hauleth/rust,aneeshusa/rust,victorvde/rust,ruud-v-a/rust,pelmers/rust,ebfull/rust,cllns/rust,AerialX/rust-rt-minimal,untitaker/rust,dwillmer/rust,mihneadb/rust,dwillmer/rust,jroesch/rust,seanrivera/rust,pelmers/rust,mihneadb/rust,dinfuehr/rust,l0kod/rust,aidancully/rust,aepsil0n/rust,pelmers/rust,rohitjoshi/rust,robertg/rust,XMPPwocky/rust,aepsil0n/rust,aidancully/rust,pshc/rust,ejjeong/rust,bombless/rust,mahkoh/rust,pshc/rust,reem/rust,reem/rust,robertg/rust,omasanori/rust,richo/rust,andars/rust,hauleth/rust,AerialX/rust-rt-minimal,gifnksm/rust,omasanori/rust,philyoon/rust,mvdnes/rust,AerialX/rust,cllns/rust,GBGamer/rust,kwantam/rust,miniupnp/rust,miniupnp/rust,nwin/rust,robertg/rust,krzysz00/rust,AerialX/rust,victorvde/rust,vhbit/rust,GBGamer/rust,robertg/rust,nwin/rust,kwantam/rust,avdi/rust,ejjeong/rust,l0kod/rust,krzysz00/rust,jroesch/rust,TheNeikos/rust,bombless/rust,omasanori/rust,aneeshusa/rust,untitaker/rust,omasanori/rust,jashank/rust,philyoon/rust,jashank/rust,ejjeong/rust,sae-bom/rust,jashank/rust,omasanori/rust,KokaKiwi/rust,ruud-v-a/rust,mvdnes/rust,vhbit/rust,zaeleus/rust,zachwick/rust,sae-bom/rust,mvdnes/rust,TheNeikos/rust,nwin/rust,ebfull/rust,dwillmer/rust,sae-bom/rust,KokaKiwi/rust,reem/rust,miniupnp/rust,krzysz00/rust,AerialX/rust-rt-minimal,hauleth/rust,jashank/rust,victorvde/rust,ebfull/rust,ruud-v-a/rust,zaeleus/rust,mahkoh/rust,pshc/rust,AerialX/rust-rt-minimal,hauleth/rust,carols10cents/rust,pelmers/rust,hauleth/rust,ejjeong/rust,avdi/rust,GBGamer/rust,carols10cents/rust,vhbit/rust,AerialX/rust,krzysz00/rust,vhbit/rust,graydon/rust,untitaker/rust,gifnksm/rust,carols10cents/rust,kwantam/rust,philyoon/rust,avdi/rust,TheNeikos/rust,zubron/rust,pelmers/rust,pshc/rust,andars/rust,dwillmer/rust,KokaKiwi/rust,zubron/rust,pshc/rust,ejjeong/rust,victorvde/rust,nwin/rust,mahkoh/rust,AerialX/rust,dwillmer/rust,jroesch/rust,aepsil0n/rust,philyoon/rust,mahkoh/rust,gifnksm/rust,XMPPwocky/rust,GBGamer/rust,graydon/rust,miniupnp/rust,kwantam/rust,miniupnp/rust,zachwick/rust,vhbit/rust,l0kod/rust,zubron/rust,graydon/rust,sae-bom/rust,ebfull/rust,mvdnes/rust,AerialX/rust,carols10cents/rust,mihneadb/rust,philyoon/rust,TheNeikos/rust,l0kod/rust,rohitjoshi/rust,aepsil0n/rust,pelmers/rust,andars/rust,nwin/rust,mdinger/rust,AerialX/rust-rt-minimal,nwin/rust,nwin/rust,untitaker/rust,rprichard/rust,aidancully/rust,untitaker/rust,dinfuehr/rust,mdinger/rust,rohitjoshi/rust,l0kod/rust,cllns/rust,richo/rust,aidancully/rust,vhbit/rust,graydon/rust,seanrivera/rust,jroesch/rust,jroesch/rust,sae-bom/rust,mihneadb/rust,avdi/rust,aepsil0n/rust,ruud-v-a/rust,andars/rust,TheNeikos/rust