Updates to blog posts and other pages

# The default can be overridden by Markdown="false" or Markdown="true".

Updates are parsed as Markdown by default if SiteConfig.BuildConfig.Markdown.Update = true

Any page can have updates that appear in the feed. Though a new page itself will not appear in the feed.

This is another update.

This one has the attribute Render which will make it appear in the post itself.

This is the second update.

It appears in the feed.

It also appears in the post when using <Update Render>.

This is the first update.

It appears in the feed but not in the post itself.

This is an update to the post. It will generate a new item in the feed.