Update changelog for 3.6.1.

debian/changelog

 tails (3.6.1) UNRELEASED; urgency=medium
 
-  * Dummy entry for next release.
+  * Security fixes
+    - Upgrade Tor Browser to 7.5.2 (MFSA 2018-08 i.e. CVE-2018-5146).
+    - Upgrade libvorbis to 1.3.5-4+deb9u2 (DSA 4140-1 aka. CVE-2018-5146).
+    - Upgrade curl to 7.52.1-5+deb9u5 (DSA 4136-1).
+    - Upgrade samba to 2:4.5.12+dfsg-2+deb9u2 (DSA 4135-1).
+
+  * Bugfixes
+    - Fix ISO build reproducibility (Closes: #15400)
 
- -- Tails developers <tails@boum.org>  Wed, 14 Mar 2018 11:46:15 +0100
+ -- Tails developers <tails@boum.org>  Fri, 16 Mar 2018 21:07:36 +0000
 
 tails (3.6) unstable; urgency=medium