Add example of multi bar with widths exceeding maximum terminal scree…

…n width in ref to issue #28

examples/multi/width.rb

@@ -0,0 +1,13 @@
+require_relative '../../lib/tty-progressbar'
+
+bars = TTY::ProgressBar::Multi.new("main [:bar] :percent")
+
+bar1 = bars.register "foo [:bar] :percent", total: 150
+bar2 = bars.register "bar [:bar] :percent", total: 250
+bar3 = bars.register "baz [:bar] :percent", total: 100
+
+th1 = Thread.new { 150.times { sleep(0.1); bar1.advance } }
+th2 = Thread.new { 250.times { sleep(0.1); bar2.advance } }
+th3 = Thread.new { 100.times { sleep(0.1); bar3.advance } }
+
+[th1, th2, th3].each(&:join)