Add basic report template

CONTRIBUTING.md

@@ -11,7 +11,7 @@ We welcome contributions from *everyone*. While contributing, please follow the
 If you'd like to help make RSpec better, here are some ways you can contribute:
 
   - by running RSpec HEAD to help us catch bugs before new releases
-  - by [reporting bugs you encounter](https://github.com/rspec/rspec-core/issues/new)
+  - by [reporting bugs you encounter](https://github.com/rspec/rspec-core/issues/new) with [report template](#report-template)
   - by [suggesting new features](https://github.com/rspec/rspec-core/issues/new)
   - by improving RSpec's [Relish](https://relishapp.com/rspec) or [API](http://rspec.info/documentation/) documentation
   - by improving [RSpec's website](http://rspec.info/) ([source](https://github.com/rspec/rspec.github.io))
@@ -30,6 +30,46 @@ These issue are ones that we be believe are best suited for new contributors to
 get started with. They represent a meaningful contribution to the project that
 should not be too hard to pull off.
 
+## Report template
+
+Having a way to reproduce your issue will be very helpful for others to help confirm, investigate and ultimately fix your issue. You can do this by providing an executable test case. To make this process easier, we have prepared one basic bug report templates for you to use as a starting point:
+
+```ruby
+# frozen_string_literal: true
+
+begin
+  require "bundler/inline"
+rescue LoadError => e
+  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
+  raise e
+end
+
+gemfile(true) do
+  source "https://rubygems.org"
+
+  gem 'aruba' # Needed to execute RSpec from Ruby code
+  gem "rspec", "3.7.0" # Activate the gem and version you are reporting the issue against.
+end
+
+puts "Ruby version is: #{RUBY_VERSION}"
+
+describe 'additions' do
+  it 'returns 2' do
+    expect(1 + 1).to eq(2)
+  end
+
+  it 'returns 1' do
+    expect(3 - 1).to eq(-1)
+  end
+end
+
+RSpec::Core::Runner.invoke
+```
+
+Simply copy the content of the appropriate template into a `.rb` file on your computer and make the necessary changes to demonstrate the issue. You can execute it by running `ruby the_file.rb` in your terminal.
+
+You can then share your executable test case as a [gist](https://gist.github.com), or simply paste the content into the issue description.
+
 ## Maintenance branches
 
 Maintenance branches are how we manage the different supported point releases