add form for /page/set-nav-menu defroute in /user/edit-page.html.

I, also, changed templated data to use 'db-data' element in databag
passed to the djula HTML template.

templates/user/edit-page.html

@@ -47,19 +47,32 @@
  });
 </script>
 
+<form action="/page/set-nav-menu" method="post">
+  <input required type="hidden" name="AUTHENTICITY-TOKEN" value="{{token}}">
+  <input required type="hidden" name="SLUG" value="{{db-data.slug}}">
+    <input type="checkbox" name="SHOW-IN-NAV"
+	   {% if db-data.enable-nav-menu == 1 %}
+	   checked
+	   {% endif %}
+    >
+    <label>Include in Nav. Menu</label>
+    <input type="submit" value="Save Changes">
+</form>
+
 <form action="/rename/page" method="post">
-    <input required type="hidden" name="AUTHENTICITY-TOKEN" value="{{token}}">
-    <input required type="hidden" name="TITLE" value="{{title}}">
+  <input required type="hidden" name="AUTHENTICITY-TOKEN" value="{{token}}">
+   <input required type="hidden" name="ID" value="{{db-data.id}}">
+    <input required type="hidden" name="SLUG" value="{{db-data.slug}}">
     <label>Title</label>
-    <input required type="text" name="NEW-TITLE" value="{{title}}">
+    <input required type="text" name="NEW-TITLE" value="{{db-data.title}}">
     <input type="submit" value="Rename Page">
 </form>
 
 <form action="/edit/page" method="post">
-    <input required type="hidden" name="AUTHENTICITY-TOKEN" value="{{token}}">
-    <input required type="hidden" name="TITLE" value="{{title}}">
-    <textarea name="PAGE-CONTENT" id="mytextarea"
-	      placeholder="Enter page content...">
+  <input required type="hidden" name="AUTHENTICITY-TOKEN" value="{{token}}">
+  <input required type="hidden" name="slug" value="{{db-data.slug}}">
+  <textarea name="PAGE-CONTENT" id="mytextarea"
+	    placeholder="Enter page content...">
     {{data}}
     </textarea>
     <!-- <input type="submit" value="Save Page"> -->