Mention the significance of leading 0 in int fn string input

https://discourse.gohugo.io/t/unable-to-cast-09-of-type-string-to-int/9614

content/functions/int.md

@@ -24,3 +24,28 @@ Useful for turning strings into numbers.
 ```
 {{ int "123" }} → 123
 ```
+
+{{% note "Usage Note" %}}
+If the input string is supposed to represent a decimal number, and if it has
+leading 0's, then those 0's will have to be removed before passing the string
+to the `int` function, else that string will be tried to be parsed as an octal
+number representation.
+
+The [`strings.TrimLeft` function](/functions/strings.trimleft/) can be used for
+this purpose.
+
+```
+{{ int ("0987" | strings.TrimLeft "0") }}
+{{ int ("00987" | strings.TrimLeft "0") }}
+```
+
+**Explanation**
+
+The `int` function eventually calls the `ParseInt` function from the Go library
+`strconv`.
+
+From its [documentation](https://golang.org/pkg/strconv/#ParseInt):
+
+> the base is implied by the string's prefix: base 16 for "0x", base 8 for "0",
+> and base 10 otherwise.
+{{% /note %}}