Explain what's benchmark/lib/load.rb [ci skip]

I'm actually not using this, but ko1 is.

1 files changed, 16 insertions, 0 deletions

diff --git a/benchmark/lib/load.rb b/benchmark/lib/load.rb
index 4d73a63323..31b770c484 100755
--- a/benchmark/lib/load.rb
+++ b/benchmark/lib/load.rb
@@ -1,2 +1,18 @@
+# How to use this file:
+#   1. write a `$(srcdir)/test.rb` like:
+=begin
+require_relative 'benchmark/lib/load'
+
+Benchmark.driver(repeat_count: 5){|x|
+  x.executable name: 'clean-miniruby', command: %w'../clean-trunk/miniruby'
+  x.executable name: 'modif-miniruby', command: %w'./miniruby'
+
+  x.report %q{
+    h = {a: 1, b: 2, c: 3, d: 4}
+  }
+}
+=end
+#
+#  2. `make run`
 $:.unshift(File.join(__dir__, '../benchmark-driver/lib'))
 require 'benchmark_driver'