wc: add words example, update characters example

pages/common/wc.md

@@ -6,7 +6,11 @@
 
 `wc -l {{file}}`
 
-- Count bytes in file:
+- Count words in file:
+
+`wc -w {{file}}`
+
+- Count characters (bytes) in file:
 
 `wc -c {{file}}`