note that integers have .to_string() method [skip ci]

docs/markdown/Reference-manual.md

@@ -1794,6 +1794,7 @@ are immutable, all operations return their results as a new string.
 
  - `is_even()` returns true if the number is even
  - `is_odd()` returns true if the number is odd
+ - `to_string()` returns the value of the number as a string.
 
 ### `boolean` object
 

docs/markdown/Syntax.md

@@ -78,6 +78,13 @@ string_var = '42'
 num = string_var.to_int()
 ```
 
+Numbers can be converted to a string:
+
+```meson
+int_var = 42
+string_var = int_var.to_string()
+```
+
 Booleans
 --