Add an entry to the release notes.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@344062 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index eac65b5..aeed10a 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -33,6 +33,9 @@
   non-superpages to a superpage if they are aligned to the superpage
   size. (`r342746 <https://reviews.llvm.org/rL342746>`_)
 
+* lld/Hexagon can now link Linux kernel and musl libc for Qualcomm
+  Hexagon ISA.
+
 * The following flags have been added: ``-z interpose``, ``-z global``
 
 COFF Improvements