README.rdoc update2

lib/README.rdoc

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+= IntervalTree
+
+Title:: the IntervalTree module using "argumanted tree"
+Author:: MISHIMA, Hiroyuki ( https://github.com/misshie )
+Copyright:: The MIT/X11 license
+
+== see also
+*description in Wikipedia http://en.wikipedia.org/wiki/Interval_tree
+*an implementstion in Python by Tyler Kahn http://forrst.com/posts/Interval_Tree_implementation_in_python-e0K    
+
+== usage
+ require "interval_tree"
+
+ itv = [(0...3), (1...4), (3...5),]
+ t = IntervalTree::Tree.new(itv)
+ p t.search(2) => [0...3, 1...4]
+ p t.search(1...3) => [0...3, 1...4, 3...5]
+
+== note
+result intervals are always returned
+in the "left-closed and right-open" style that can be expressed
+by three-dotted Range object literals (first...last)
+
+Full-closed intervals "(first..last)" for tree are internally
+converted to half-closed intervals.