rss-bot: Linkify RSS entry title.

This makes our life a bit nicer if the message is super-long,
because then even when it's "condensed", we still get a link
to the actual article.

(imported from commit 32e70d29cb702ce73f6cd0c04dbc58457cd2e6b5)

demos/rss-bot

@@ -114,7 +114,8 @@ def compute_entry_hash(entry):
     return hashlib.md5(entry.id + entry_time).hexdigest()
 
 def send_zulip(entry, feed_name):
-    content = "**%s**\n%s\n%s" % (entry.title,
+    content = "**[%s](%s)**\n%s\n%s" % (entry.title,
+                                  entry.link,
                                   strip_tags(entry.summary),
                                   entry.link)
     message = {"type": "stream",