Add specs of snippets from docs

spec/docs/getting_started_spec.cr

@@ -0,0 +1,23 @@
+require "../spec_helper"
+
+Spectator.describe String do
+  subject { "foo" }
+
+  describe "#==" do
+    context "with the same value" do
+      let(value) { subject.dup }
+
+      it "is true" do
+        is_expected.to eq(value)
+      end
+    end
+
+    context "with a different value" do
+      let(value) { "bar" }
+
+      it "is false" do
+        is_expected.to_not eq(value)
+      end
+    end
+  end
+end