Clarify documentation about "except clauses"
Clarify documentation about "except clauses"

They're called type conversions. Type casts are done with cast[T](...)
and are not type safe.

nafsaka/Nim,fredericksilva/Nim,kirbyfan64/Nim,jfhg/Nim,Dhertz/Nim,Salafit/Nim,mbaulch/Nim,bvssvni/Nim,gokr/Nim,Senketsu/Nim,mbaulch/Nim,nafsaka/Nim,tmm1/Nim,singularperturbation/Nim,SSPkrolik/Nim,tmm1/Nim,jfhg/Nim,msmith491/Nim,SSPkrolik/Nim,tmm1/Nim,SSPkrolik/Nim,BlaXpirit/nim,zachaysan/Nim,dom96/Nim,russpowers/Nim,MrJohz/Nim,MrJohz/Nim,douglas-larocca/Nim,xland/Nim,greyanubis/Nim,endragor/Nim,sarvex/Nim-lang,reactormonk/nim,MrJohz/Nim,fredericksilva/Nim,sferik/Nim,tmm1/Nim,judofyr/Nim,msmith491/Nim,dom96/Nim,Senketsu/Nim,reactormonk/nim,fmamud/Nim,douglas-larocca/Nim,greyanubis/Nim,jfhg/Nim,Senketsu/Nim,BlaXpirit/nim,jsanjuas/Nim,haiodo/Nim,reactormonk/nim,singularperturbation/Nim,kirbyfan64/Nim,Senketsu/Nim,sarvex/Nim-lang,nanoant/Nim,kirbyfan64/Nim,bvssvni/Nim,Salafit/Nim,bvssvni/Nim,Matt14916/Nim,nanoant/Nim,fredericksilva/Nim,jfhg/Nim,SSPkrolik/Nim,gokr/Nim,BlaXpirit/nim,msmith491/Nim,nanoant/Nim,fredericksilva/Nim,JCavallo/Nim,jfhg/Nim,sarvex/Nim-lang,fredericksilva/Nim,Salafit/Nim,greyanubis/Nim,russpowers/Nim,Matt14916/Nim,tulayang/Nim,douglas-larocca/Nim,Matt14916/Nim,fmamud/Nim,Dhertz/Nim,judofyr/Nim,sferik/Nim,Salafit/Nim,singularperturbation/Nim,fmamud/Nim,singularperturbation/Nim,BlaXpirit/nim,judofyr/Nim,bvssvni/Nim,fmamud/Nim,JCavallo/Nim,douglas-larocca/Nim,zachaysan/Nim,russpowers/Nim,fredericksilva/Nim,xland/Nim,nafsaka/Nim,haiodo/Nim,xland/Nim,reactormonk/nim,jsanjuas/Nim,gokr/Nim,jsanjuas/Nim,haiodo/Nim,xland/Nim,dom96/Nim,dom96/Nim,Matt14916/Nim,SSPkrolik/Nim,kirbyfan64/Nim,JCavallo/Nim,SSPkrolik/Nim,Salafit/Nim,nimLuckyBull/Nim,nimLuckyBull/Nim,Dhertz/Nim,JCavallo/Nim,BlaXpirit/nim,MrJohz/Nim,nanoant/Nim,fredericksilva/Nim,nanoant/Nim,bvssvni/Nim,Senketsu/Nim,greyanubis/Nim,nimLuckyBull/Nim,tulayang/Nim,singularperturbation/Nim,sarvex/Nim-lang,mbaulch/Nim,judofyr/Nim,judofyr/Nim,xland/Nim,greyanubis/Nim,sarvex/Nim-lang,tulayang/Nim,bvssvni/Nim,JCavallo/Nim,dom96/Nim,sarvex/Nim-lang,haiodo/Nim,fmamud/Nim,jsanjuas/Nim,tulayang/Nim,MrJohz/Nim,judofyr/Nim,Salafit/Nim,nafsaka/Nim,gokr/Nim,Matt14916/Nim,haiodo/Nim,kirbyfan64/Nim,zachaysan/Nim,reactormonk/nim,nimLuckyBull/Nim,greyanubis/Nim,sferik/Nim,gokr/Nim,endragor/Nim,tulayang/Nim,zachaysan/Nim,msmith491/Nim,zachaysan/Nim,kirbyfan64/Nim,singularperturbation/Nim,nanoant/Nim,SSPkrolik/Nim,Dhertz/Nim,mbaulch/Nim,nafsaka/Nim,reactormonk/nim,zachaysan/Nim,tmm1/Nim,russpowers/Nim,kirbyfan64/Nim,Salafit/Nim,nanoant/Nim,douglas-larocca/Nim,fmamud/Nim,sferik/Nim,BlaXpirit/nim,Senketsu/Nim,reactormonk/nim,russpowers/Nim,sferik/Nim,russpowers/Nim,dom96/Nim,sferik/Nim,kirbyfan64/Nim,mbaulch/Nim,singularperturbation/Nim,BlaXpirit/nim,Matt14916/Nim,greyanubis/Nim,xland/Nim,endragor/Nim,reactormonk/nim,xland/Nim,jsanjuas/Nim,endragor/Nim,tmm1/Nim,msmith491/Nim,endragor/Nim,Senketsu/Nim,gokr/Nim,jfhg/Nim,Dhertz/Nim,endragor/Nim,jsanjuas/Nim,MrJohz/Nim,mbaulch/Nim,MrJohz/Nim,russpowers/Nim,jfhg/Nim,sferik/Nim,gokr/Nim,msmith491/Nim,JCavallo/Nim,judofyr/Nim,mbaulch/Nim,haiodo/Nim,Dhertz/Nim,jsanjuas/Nim,judofyr/Nim,msmith491/Nim,tulayang/Nim,fmamud/Nim,fredericksilva/Nim,nafsaka/Nim,endragor/Nim,nimLuckyBull/Nim,BlaXpirit/nim,zachaysan/Nim,gokr/Nim,nimLuckyBull/Nim,douglas-larocca/Nim,JCavallo/Nim,douglas-larocca/Nim,Dhertz/Nim,nimLuckyBull/Nim,sarvex/Nim-lang,dom96/Nim,sferik/Nim,haiodo/Nim,tmm1/Nim,nafsaka/Nim,bvssvni/Nim,SSPkrolik/Nim,douglas-larocca/Nim,Matt14916/Nim