Use autocomplete="off" in buttons plugin docs examples

Refs #13875.

docs/_includes/js/buttons.html

@@ -44,26 +44,26 @@
   <div class="bs-example" style="padding-bottom: 24px;">
     <div class="btn-group" data-toggle="buttons">
       <label class="btn btn-primary active">
-        <input type="checkbox" checked> Option 1 (pre-checked)
+        <input type="checkbox" autocomplete="off" checked> Option 1 (pre-checked)
       </label>
       <label class="btn btn-primary">
-        <input type="checkbox"> Option 2
+        <input type="checkbox" autocomplete="off"> Option 2
       </label>
       <label class="btn btn-primary">
-        <input type="checkbox"> Option 3
+        <input type="checkbox" autocomplete="off"> Option 3
       </label>
     </div>
   </div><!-- /example -->
 {% highlight html %}
 <div class="btn-group" data-toggle="buttons">
   <label class="btn btn-primary active">
-    <input type="checkbox" checked> Option 1 (pre-checked)
+    <input type="checkbox" autocomplete="off" checked> Option 1 (pre-checked)
   </label>
   <label class="btn btn-primary">
-    <input type="checkbox"> Option 2
+    <input type="checkbox" autocomplete="off"> Option 2
   </label>
   <label class="btn btn-primary">
-    <input type="checkbox"> Option 3
+    <input type="checkbox" autocomplete="off"> Option 3
   </label>
 </div>
 {% endhighlight %}
@@ -77,26 +77,26 @@
   <div class="bs-example" style="padding-bottom: 24px;">
     <div class="btn-group" data-toggle="buttons">
       <label class="btn btn-primary active">
-        <input type="radio" name="options" id="option1" checked> Option 1 (preselected)
+        <input type="radio" name="options" id="option1" autocomplete="off" checked> Option 1 (preselected)
       </label>
       <label class="btn btn-primary">
-        <input type="radio" name="options" id="option2"> Option 2
+        <input type="radio" name="options" id="option2" autocomplete="off"> Option 2
       </label>
       <label class="btn btn-primary">
-        <input type="radio" name="options" id="option3"> Option 3
+        <input type="radio" name="options" id="option3" autocomplete="off"> Option 3
       </label>
     </div>
   </div><!-- /example -->
 {% highlight html %}
 <div class="btn-group" data-toggle="buttons">
   <label class="btn btn-primary active">
-    <input type="radio" name="options" id="option1" checked> Option 1 (preselected)
+    <input type="radio" name="options" id="option1" autocomplete="off" checked> Option 1 (preselected)
   </label>
   <label class="btn btn-primary">
-    <input type="radio" name="options" id="option2"> Option 2
+    <input type="radio" name="options" id="option2" autocomplete="off"> Option 2
   </label>
   <label class="btn btn-primary">
-    <input type="radio" name="options" id="option3"> Option 3
+    <input type="radio" name="options" id="option3" autocomplete="off"> Option 3
   </label>
 </div>
 {% endhighlight %}