Update release notes

Author: hbons

RELEASE_NOTES.txt

@@ -1,12 +1,12 @@
-3.28.0 (Sun Mar 18, 2018):
+3.28.0 (Sat 14 Jul, 2018):
 
     Fixed a bunch of crashes and lots of under-the-hood improvements.
     SparkleShare will now follow the GNOME release schedule and version 
     number scheme as much as possible.
 
-    Please make sure to install the TopIcons GNOME Shell extension
-    (https://extensions.gnome.org/extension/495/topicons/) to display
-    status icons in GNOME 3.26 or later.
+    Please make sure to install the AppIndicator Support GNOME Shell extension
+    (https://extensions.gnome.org/extension/615/appindicator-support/) to display
+    status icons in GNOME 3.26 or later. Or start with --status-icon=gtk.
 
     Linux:
     - Use the Meson build system
@@ -18,7 +18,7 @@
     - Fix the system font in eventlog and related crash
     - Fix hang when quitting the app
 
-    Special thanks to Renpytom for supporting the project on Patreon.
+    Special thanks to Thiago Santos and Renpytom for supporting the project on Patreon.
 
 
 2.0.1 (Tue 19 Dec, 2017):