docs(datepicker): fix demo input type

- Fixes input demo type and adds note on native datepickers

Closes #5115
Closes #5239

Author: deeg

Diff for: src/datepicker/docs/demo.html

@@ -31,7 +31,7 @@ <h4>Popup</h4>
 
         <div class="col-md-6">
             <p class="input-group">
-              <input type="date" class="form-control" uib-datepicker-popup ng-model="dt" is-open="popup2.opened" min-date="minDate" max-date="maxDate" datepicker-options="dateOptions" date-disabled="disabled(date, mode)" ng-required="true" close-text="Close" />
+              <input type="text" class="form-control" uib-datepicker-popup ng-model="dt" is-open="popup2.opened" min-date="minDate" max-date="maxDate" datepicker-options="dateOptions" date-disabled="disabled(date, mode)" ng-required="true" close-text="Close" />
               <span class="input-group-btn">
                 <button type="button" class="btn btn-default" ng-click="open2()"><i class="glyphicon glyphicon-calendar"></i></button>
               </span>

Diff for: src/datepicker/docs/readme.md

@@ -235,3 +235,5 @@ Depending on datepicker's current mode, the date may refer either to day, month
 **Notes**
 
 If the date a user enters falls outside of the min-/max-date range, a `dateDisabled` validation error will show on the form.
+
+If using this directive on input type date, a native browser datepicker could also appear.