[S32/Containers] explain uniq/squish a bit more
[S32/Containers] explain uniq/squish a bit more

- both uniq and squish preserve order
- omit some implementation details which shouldn't be
  in the spec
- give examples

prammer/specs,prammer/specs,perl6/specs,tokuhirom/specs,prammer/specs,tokuhirom/specs,tokuhirom/specs,perl6/specs