default to num instead of variable for toString (#1977)

* default to num instead of variable for toString

* to text instead of toString

* converToText

docs/reference/text/convert-to-text.md

@@ -1,7 +1,7 @@
-# to string
+# convert to text
 
 Converts a value into a text representation.
 
 ```sig
-toString(123)
+convertToText(123)
 ```