Adding examples of using expect syntax (#2213)

As discussed during the Chef Community Summit 2017 in Seattle, many
more technical users wish to use `expect` syntax and wish to see
more examples of how to do so with InSpec resources.

Signed-off-by: Adam Leff <adam@leff.co>

docs/profiles.md

@@ -331,3 +331,40 @@ The tests in `example.rb` can now access this file:
         it { should be_listening }
       end
     end
+
+# "should" vs. "expect" syntax
+
+Users familiar with the RSpec testing framework may know that there are two ways to write test statements: `should` and `expect`. The RSpec community decided that `expect` is the preferred syntax. However, InSpec recommends the `should` syntax as it tends to read more easily to those users who are not as technical.
+
+InSpec will continue to support both methods of writing tests. Consider this `file` test:
+
+    describe file('/tmp/test.txt') do
+      it { should be_file }
+    end
+
+This can be re-written with `expect` syntax
+
+    describe file('/tmp/test.txt') do
+      it 'should be a file' do
+        expect(subject).to(be_file)
+      end
+    end
+
+The output of both of the above examples looks like this:
+
+    File /tmp/test.txt
+       ✔  should be a file
+
+In addition, you can make use of the `subject` keyword to further control your output if you choose:
+
+    describe 'test file' do
+      subject { file('/tmp/test.txt') }
+      it 'should be a file' do
+        expect(subject).to(be_file)
+      end
+    end
+
+... which will render the following output:
+
+    test file
+      ✔  should be a file