docs(filters): fix minor typographical error

Fix a typographical error "it's" -> "its" in the dateFilter
documentation

src/ng/filter/filters.js

@@ -307,7 +307,7 @@ var DATE_FORMATS_SPLIT = /((?:[^yMdHhmsaZE']+)|(?:'(?:[^']|'')*')|(?:E+|y+|M+|d+
  *   (e.g. `"h o''clock"`).
  *
  * @param {(Date|number|string)} date Date to format either as Date object, milliseconds (string or
- *    number) or various ISO 8601 datetime string formats (e.g. yyyy-MM-ddTHH:mm:ss.SSSZ and it's
+ *    number) or various ISO 8601 datetime string formats (e.g. yyyy-MM-ddTHH:mm:ss.SSSZ and its
  *    shorter versions like yyyy-MM-ddTHH:mmZ, yyyy-MM-dd or yyyyMMddTHHmmssZ). If no timezone is
  *    specified in the string input, the time is considered to be in the local timezone.
  * @param {string=} format Formatting rules (see Description). If not specified,