Thanks Benoit. I've fixed that typo and used the same explanation for both uniq and uniq!. Also made some other changes to other sections on the Array.
This issue was solved with changeset r33453.
Alvaro, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.
array.c (rb_ary_initialize): Improve explanation of Array.new
parameters. Patch by Alvaro Pereyra Rabanal. [Ruby 1.9 - Bug #5425]