Update 786-string-lower.markdown

Author: Joe7M

_build/reference/786-string-lower.markdown

@@ -1,7 +1,14 @@
 # LOWER
 
-> LOWER (s)
+> lc = LOWER (s)
 
-Converts the string s to lower case.
+Converts the string `s` to the lower-case string `lc`.
+
+### Example:
+
+```
+s = "TeSt-STrinG"
+print lower(s)   ' Output: test-string
+```