add reCaptcha parts in form

samples/hugo-partial-contact-form.html

@@ -3,6 +3,9 @@
    <fieldset>
       <legend>Please fill in the form to submit your request</legend>
       <form action="https://contact-request-endpoint/" method="post">
+         <!-- uncomment this div block when enabling reCaptcha
+         <script src="https://www.google.com/recaptcha/api.js"></script>
+         -->
          <div class="form-item">
             <label for="name">Name</label>
             <input type="text" name="name" id="name"  placeholder="Mr. Smith" />
@@ -31,6 +34,9 @@
             <input type="hidden" name="target" id="target"  value="demo" />
          </div>
          {{ end }}
+         <!-- uncomment the below div when enabling reCaptcha
+         <div class="g-recaptcha" data-sitekey="{{.Site.Params.reCaptchaPrivateKey}}"></div>
+         -->
          <input  class="button"  type="submit" value="Submit">
       </form>
    </fieldset>