Update README.md

updated with new citation info

README.md

@@ -8,13 +8,14 @@
 If you use this program, please cite:
 
 ```
-James B Pease, Matthew W. Hahn.
-"Detection and Polarization of Introgression in a Five-taxon Phylogeny" In revision.
-http://biorxiv.org/content/early/2014/05/01/004689.short
-doi: 10.1101/004689 
+James B Pease, Matthew W. Hahn .
+"Detection and Polarization of Introgression in a Five-taxon Phylogeny" 
+2015. Systematic Biology. 
+doi: 10.1093/sysbio/syv023
 ```
 ## Version History
-* v. 2014-02-07 Re-release version on GitHub
+* v. 2015-02-07 Re-release version on GitHub
+* v. 2015-04-17 Minor updates and citation information, Publication Release Version
 
 ## Requirements:
 * Python 2.6+ (2.6+ and 3.x compatible)
@@ -124,4 +125,4 @@ This file is part of dfoil.
 
 dfoil is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as publihed by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
 
-dfoil is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Foobar.  If not, see (http://www.gnu.org/licenses/).
+dfoil is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Foobar.  If not, see (http://www.gnu.org/licenses/).