Add skiboot-5.3.0 release notes

Signed-off-by: Stewart Smith <[email protected]>

doc/release-notes/skiboot-5.3.0.txt

@@ -0,0 +1,16 @@
+skiboot-5.3.0
+-------------
+
+skiboot-5.3.0 was released on Tuesday August 2nd, 2016.
+
+skiboot-5.3.0 is the first stable release of skiboot 5.3, the new stable
+release of skiboot, which will take over from the 5.2.x series which was
+first released Wednesday March 16th, 2016.
+
+skiboot-5.3.0 contains all bug fixes as of skiboot-5.1.17 and skiboot-5.2.5.
+
+Changes over skiboot-5.3.0-rc2:
+- Adopt libtool rules for soname versioning for libflash
+
+See skiboot-5.3.0-rc2 and skiboot-5.3.0-rc1 release notes for a complete
+list of changes from skiboot-5.2.0.