Use buck rule for ReleaseNotes instead of Makefile

This eliminates the last Makefile in our code base.

Also change the section style within ReleaseNotes from asciidoc style to
asciidoctor style.

Also I feel that put images/link.png under ReleaseNotes and deal with
all the resource packing is too stupid, so I used the unicode emoji
instead of the picture ("🔗"). If this is too crazy, we can also use "#"
instead :) This also affects documentation rendering.

Other side effects:

1. The css of release notes switched from default asciidoc css into
default asciidoctor css.
2. The section anchors for ReleaseNotes/index.html changed from "2_13"
to "s2_13", because asciidoctorj is unhappy with anchors without
letters.

Change-Id: I4adf2ce090385cc6b699445012f10a009892aaac
diff --git a/ReleaseNotes/ReleaseNotes-2.0.8.txt b/ReleaseNotes/ReleaseNotes-2.0.8.txt
index 4b2d10a5..89e7fdd 100644
--- a/ReleaseNotes/ReleaseNotes-2.0.8.txt
+++ b/ReleaseNotes/ReleaseNotes-2.0.8.txt
@@ -1,5 +1,4 @@
-Release notes for Gerrit 2.0.8
-==============================
+= Release notes for Gerrit 2.0.8
 
 Gerrit 2.0.8 is now available in the usual location:
 
@@ -14,8 +13,7 @@
 This version has some major bug fixes for JGit.  I strongly encourage people to upgrade, we had a number of JGit bugs identified last week, all of them should be fixed in this release.
 
 
-New Features
-------------
+== New Features
 * Allow users to subscribe to submitted change events
 +
 Someone asked me on an IRC channel to have Gerrit send emails when changes are actually merged into a project.  This is what triggered the schema change; there is a new checkbox on the Watched Projects list under Settings to subscribe to these email notifications.
@@ -33,15 +31,13 @@
 +
 The reflogs now contain the remote user's IP address when Gerrit makes edits, resulting in slightly more detail than was there before.
 
-Bug Fixes
----------
+== Bug Fixes
 * Make sure only valid ObjectIds can be passed into git d...
 * GERRIT-92  Upgrade JGit to 0.4.0-262-g3c268c8
 +
 The JGit bug fixes are rather major.  I would strongly encourage upgrading.
 
-Other Changes
--------------
+== Other Changes
 * Start 2.0.8 development
 * Upgrade MINA SSHD to SVN trunk 755651
 * Fix a minor whitespace error in ChangeMail