Update 780-string-hex.markdown

Author: Joe7M

_build/reference/780-string-hex.markdown

@@ -4,4 +4,10 @@
 
 Returns the hexadecimal value of x as string.
 
+### Example
 
+```
+print hex(255)      ' output: FF
+print bin(8)        ' output: 1000
+print oct(16)       ' output: 20
+```