* NEWS-2.1.0: Mention that step can accept a 0 unit. See #9575

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45234 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* numeric.c: Mention that Float::DIG is the minimum number
  of siginificant digits. See #9191

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45235 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* proc.c: Tweak rdoc for consistent whitespace

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45236 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* proc.c: Modify rdoc of Proc#arity to fit with current behavior.
  See #5694

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45237 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* proc.c: Complete rdoc of Proc#arity regarding keyword arguments.
  See #8072 and #9299.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45238 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* README.EXT: [DOC] Remove needless char

* README.EXT.ja: ditto


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45239 b2dd03c8-39d4-4d8f-98ff-823fe69b080e