explicitely name n in slice_head in recursiveCA-demo

Resolves #10

Change-Id: Ib23d7f2791cd1832b069a396e9f5227940835339
diff --git a/demo/recursiveCA.R b/demo/recursiveCA.R
index e07d4d7..ce2be8b 100644
--- a/demo/recursiveCA.R
+++ b/demo/recursiveCA.R
@@ -20,7 +20,7 @@
   mutate(LVC = sprintf("[%s](%s)", example, webUIRequestUrl)) %>%
   { . ->> ca } %>%
   select(LVC, logDice, pmi, ll) %>%
-  slice_head(50) %>%
+  slice_head(n = 50) %>%
   kable(format = "pipe", digits = 2)  %>%
   cat(file = mdFile, sep = "\n")