Describe new REST endpoints in 2.9 release notes

Change-Id: I4f45a1a14fdbd7cff846bf66f2a4bbf1ac33c0a1
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

ReleaseNotes/ReleaseNotes-2.9.txt

diff --git a/ReleaseNotes/ReleaseNotes-2.9.txt b/ReleaseNotes/ReleaseNotes-2.9.txt
index f65fddd..2cdc26a 100644
--- a/ReleaseNotes/ReleaseNotes-2.9.txt
+++ b/ReleaseNotes/ReleaseNotes-2.9.txt
@@ -92,6 +92,13 @@
 ~~~~~~~~
 
 
+Projects
+^^^^^^^^
+
+
+* link:https://gerrit-documentation.storage.googleapis.com/Documentation/2.9/rest-api-projects.html#get-content[
+Get content of a file from HEAD of a branch].
+
 Documentation
 ^^^^^^^^^^^^^