docs: add 2 DOIs for enron (#36)

Author: maelle

R/enron.R

@@ -51,7 +51,7 @@
 #'   C.E. Priebe, J.M. Conroy, D.J. Marchette, and Y. Park,
 #'   Scan Statistics on Enron Graphs Computational and Mathematical
 #'   Organization Theory, Volume 11, Number 3, p229 - 247, October 2005,
-#'   Springer Science+Business Media B.V.
+#'   Springer Science+Business Media B.V. \doi{10.1007/s10588-005-5378-z}
 #'
 #'   C.E. Priebe, J.M. Conroy, D.J. Marchette, and Y. Park,
 #'   Scan Statistics on Enron Graphs, SIAM International Conference on
@@ -83,7 +83,7 @@
 #'
 #'   Y. Park, C.E. Priebe, A. Youssef, Anomaly Detection in Time Series of
 #'   Graphs using Fusion of Invariants, Computational and Mathematical
-#'   Organization Theory, submitted, 2010.
+#'   Organization Theory, submitted, 2010. \doi{10.1109/JSTSP.2012.2233712}
 #' @source
 #'   <http://www.cis.jhu.edu/~parky/Enron/>
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