[sil.rst] Fix invalid reStructuredText syntax
[sil.rst] Fix invalid reStructuredText syntax

* 'Any' isn't defined anywhere, so the references to that are invalid.
* Starting a literal block but not having any leading whitespace in the next line
   causes "Literal block expected; none found."

This breaks the build when sphinx is installed.

benlangmuir/swift,apple/swift,jmgc/swift,parkera/swift,tkremenek/swift,benlangmuir/swift,parkera/swift,hooman/swift,parkera/swift,xwu/swift,ahoppen/swift,rudkx/swift,gregomni/swift,apple/swift,hooman/swift,tkremenek/swift,JGiola/swift,hooman/swift,jmgc/swift,gregomni/swift,gregomni/swift,roambotics/swift,roambotics/swift,JGiola/swift,benlangmuir/swift,ahoppen/swift,jmgc/swift,rudkx/swift,gregomni/swift,parkera/swift,atrick/swift,jmgc/swift,ahoppen/swift,glessard/swift,glessard/swift,xwu/swift,hooman/swift,gregomni/swift,glessard/swift,atrick/swift,parkera/swift,xwu/swift,jmgc/swift,rudkx/swift,hooman/swift,parkera/swift,ahoppen/swift,roambotics/swift,glessard/swift,JGiola/swift,jmgc/swift,jmgc/swift,atrick/swift,JGiola/swift,tkremenek/swift,apple/swift,hooman/swift,JGiola/swift,rudkx/swift,gregomni/swift,roambotics/swift,apple/swift,xwu/swift,JGiola/swift,glessard/swift,xwu/swift,parkera/swift,ahoppen/swift,roambotics/swift,apple/swift,rudkx/swift,benlangmuir/swift,benlangmuir/swift,rudkx/swift,xwu/swift,ahoppen/swift,parkera/swift,apple/swift,benlangmuir/swift,atrick/swift,tkremenek/swift,atrick/swift,glessard/swift,tkremenek/swift,tkremenek/swift,tkremenek/swift,atrick/swift,xwu/swift,roambotics/swift,hooman/swift