[doc] updated CHANGELOG (new release 3.1.0)

CHANGELOG

@@ -1,34 +1,49 @@
 Unreleased yet (in development)
 ===============================
 
+.. Features added
+.. --------------
+
+.. Changes
+.. -------
+
+.. Dependencies
+.. ------------
+
+.. Bugs fixed
+.. ----------
+
+.. Deprecated
+.. ----------
+
+.. Documentation
+.. -------------
+
+
+-----------------------------------------------------------------
+
+Release 3.1.0 (released `Dec 17, 2020 <https://github.com/SimonRohou/tubex-lib/releases/tag/v3.0.14>`_)
+=======================================================================================================
+
+`Commits since previous release 3.0.13 <https://github.com/SimonRohou/tubex-lib/compare/v3.0.13...v3.1.0>`_
+
 Features added
 --------------
 
 * :commit:`465d1e0908695df2bb99d5c9b2ec3a79f54bd0da`: added example of Linobs (for each :math:`\delta` parameter)
 * :commit:`1493fb8ccd92eee502b5dea6493a9ac3ef060611`: area computation of polygons
 * :commit:`37306bcad7c3945c2e4fc71fdb932e23bd940a1f`: new ``CtcLohner`` contractor with example
 
-
 Changes
 -------
 
 * :commit:`1041e3f42f4a8144d84bd43f2bb28f94256f60b5`: changed interface of ``CtcPicard`` contractor
 
-
 Dependencies
 ------------
 
 * :commit:`c18cdad6f1aa5c229ad31928eaadf76b81d428bf`: added CAPD - IBEX conversion functions
-
-
-.. Bugs fixed
-.. ----------
-
-.. Deprecated
-.. ----------
-
-.. Documentation
-.. -------------
+* Eigen is now a dependency of Tubex
 
 
 -----------------------------------------------------------------