Merge ns-3.45-release branch

Author: tomhenderson

RELEASE_NOTES.md

@@ -14,6 +14,9 @@ and references prefixed by '!' refer to a
 
 ## Release 3.45
 
+This release is available from:
+<https://www.nsnam.org/release/ns-3.45.tar.bz2>
+
 ### Supported platforms
 
 This release is intended to work on systems with the following minimal