gnu: r-nnet: Move to set of recommended R packages.

* gnu/packages/machine-learning.scm (r-nnet): Move from here...
* gnu/packages/statistics.scm (r-nnet): ...to here because the other
recommended R packages are here.

gnu/packages/machine-learning.scm

@@ -460,25 +460,6 @@ adaptive sparsity and the Wong algorithm for adaptively sparse gaussian
 geometric models.")
     (license license:lgpl3+)))
 
-(define-public r-nnet
-  (package
-    (name "r-nnet")
-    (version "7.3-12")
-    (source
-     (origin
-       (method url-fetch)
-       (uri (cran-uri "nnet" version))
-       (sha256
-        (base32
-         "17amqnw9dpap2w8ivx53hxha2xrm0drwfnj32li0xk41hlz548r7"))))
-    (build-system r-build-system)
-    (home-page "http://www.stats.ox.ac.uk/pub/MASS4/")
-    (synopsis "Feed-forward neural networks and multinomial log-linear models")
-    (description
-     "This package provides functions for feed-forward neural networks with a
-single hidden layer, and for multinomial log-linear models.")
-    (license (list license:gpl2+ license:gpl3+))))
-
 (define-public r-kernlab
   (package
     (name "r-kernlab")

gnu/packages/statistics.scm

@@ -453,6 +453,25 @@ parameter estimation by GCV, REML or UBRE/AIC.  The library includes a
 distributions beyond the exponential family.")
    (license license:gpl2+)))
 
+(define-public r-nnet
+  (package
+    (name "r-nnet")
+    (version "7.3-12")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (cran-uri "nnet" version))
+       (sha256
+        (base32
+         "17amqnw9dpap2w8ivx53hxha2xrm0drwfnj32li0xk41hlz548r7"))))
+    (build-system r-build-system)
+    (home-page "http://www.stats.ox.ac.uk/pub/MASS4/")
+    (synopsis "Feed-forward neural networks and multinomial log-linear models")
+    (description
+     "This package provides functions for feed-forward neural networks with a
+single hidden layer, and for multinomial log-linear models.")
+    (license (list license:gpl2+ license:gpl3+))))
+
 (define-public r-bit
   (package
     (name "r-bit")