Fix HTML clipboard import

jQuery's .html() method escapes contained text (e.g. '<' becomes
'&lt;'). This confuses the turndown parser, which then only performs
unescaping, but does not convert to markdown.
By using .text() instead, the unescaped content is returned and turndown
can correctly generate markdown.

Signed-off-by: David Mehren <git@herrmehren.de>

public/js/index.js

@@ -1583,7 +1583,7 @@ $('#clipboardModalClear').click(function () {
   $('#clipboardModalContent').html('')
 })
 $('#clipboardModalConfirm').click(function () {
-  const data = $('#clipboardModalContent').html()
+  const data = $('#clipboardModalContent').text()
   if (data) {
     parseToEditor(data)
     $('#clipboardModal').modal('hide')