Fix whitespace trimming for note callout shortcode

Use the same whitespace trimming that the other callout shortcodes
(warning, caution) use, and avoid excessive newline removal.

Author: Tim Bannister

layouts/shortcodes/note.html

@@ -1,3 +1,3 @@
 <blockquote class="note">
-  <div><strong>{{ T "note" }}</strong> {{ replaceRE "\\s+|\n" " " .Inner | markdownify }}</div>
+  <div><strong>{{ T "note" }}</strong> {{ trim .Inner " \n" | markdownify }}</div>
 </blockquote>