Consistently refer to Markdown with a capital

tildes/static/js/behaviors/comment-reply-button.js

@@ -42,7 +42,7 @@ $.onmount('[data-js-comment-reply-button]', function() {
         textarea.setAttribute('id', markdownID);
         textarea.setAttribute('name', 'markdown');
         textarea.setAttribute('class', 'form-input');
-        textarea.setAttribute('placeholder', 'Comment text (markdown)');
+        textarea.setAttribute('placeholder', 'Comment text (Markdown)');
         textarea.setAttribute('data-js-ctrl-enter-submit-form', '');
         textarea.setAttribute('data-js-auto-focus', '');
 

tildes/tildes/templates/macros/forms.jinja2

@@ -7,7 +7,7 @@
     class="form-input"
     id="{{ id }}"
     name="markdown"
-    placeholder="Text (markdown)"
+    placeholder="Text (Markdown)"
     data-js-ctrl-enter-submit-form
     {% if auto_focus %}data-js-auto-focus{% endif %}
   >{% if text %}{{ text }}{% endif %}</textarea>