Suffix forms of rescue and ensure are not documented

[HertzDevil]

x rescue y is equivalent to:

begin
  x
rescue
  y
end

x ensure y is equivalent to:

begin
  x
ensure
  y
end

It appears they are not documented here yet.

From https://forum.crystal-lang.org/t/bug-trying-to-downcast-tcpsocket-crystal-virtualtype-tcpsocket-crystal-nongenericclasstype/7413/2

[sol-vin]

on it 🫡