update documentation

Author: sairamsrinivasan

README.md

@@ -257,10 +257,26 @@ RSpec.describe Article do
 end
 
 # when the touch option is provided, then we can also verify that it is set.
+
+# by default, with_touch matches true when no parameters are provided.
+describe Article do
+  it { is_expected.to belong_to(:author).of_type(User).as_inverse_of(:articles).with_index.with_touch }
+end
+
+# parameters are supported for explicit matching.
+describe Comment do
+  it { is_expected.to be_embedded_in(:article).as_inverse_of(:comments).with_polymorphism.with_touch(true) }
+end
+
 describe Permalink do
   it { is_expected.to be_embedded_in(:linkable).as_inverse_of(:link).with_touch(false) } 
 end
 
+# touch can also take a symbol represneting a field on the parent to touch.
+describe Record do
+  it { is_expected.to belong_to(:user).as_inverse_of(:record).with_touch(:record_updated_at) }
+end
+
 RSpec.describe Comment do
   it { is_expected.to be_embedded_in(:article).as_inverse_of(:comments) }
   it { is_expected.to belong_to(:user).as_inverse_of(:comments) }