Add wordFrequency function

Resolves #1

Change-Id: Ifba8630d09559c1c3c31343fbdc3c849dae7d4ca
diff --git a/NAMESPACE b/NAMESPACE
index cc83af3..c182313 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -13,6 +13,7 @@
 export(syntagmaticNeighbours)
 export(vocabSize)
 export(wordEmbedding)
+export(wordFrequency)
 importFrom(httr2,req_perform)
 importFrom(httr2,req_url_path_append)
 importFrom(httr2,req_url_query)