Update release_notes.txt

To include pending changes to 7.2.7 release

java/release_notes.txt

@@ -1,14 +1,12 @@
 Mar 09, 2016: libphonenumber-7.2.7
+Code changes:
+ - Update nationalPrefixOptionalWhenFormatting documentation.
 Metadata changes:
  - Updated phone metadata for region code(s): CN, IN, MO, TK
  - Updated short number metadata for region code(s): FR
  - Updated carrier data for country calling code(s): 853 (en)
  - Updated / refreshed time zone meta data.
 
-Pending changes:
-Code changes:
- - Update nationalPrefixOptionalWhenFormatting documentation.
-
 Feb 25, 2016: libphonenumber-7.2.6
 Metadata changes:
  - Updated phone metadata for region code(s): DJ, MA, NA, US