[DOC] Correct a couple of typos in comments by @dvsuresh [Fixes GH-482]

* doc/ChangeLog-YARV:  Correct a typo in comment
* lib/rubygems/specification.rb:  ditto.
* test/rexml/data/tutorial.xml:  ditto.
* test/ruby/test_settracefunc.rb:  ditto.
* tool/instruction.rb:  ditto.

https://github.com/ruby/ruby/pull/482
[ci-skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44208 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* remove trailing spaces.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44209 b2dd03c8-39d4-4d8f-98ff-823fe69b080e