Revert r367941 "Add a note to the release not about a potentially bre…

…aking optimization"

The note was moved to the release_90 branch in r367997.

llvm-svn: 367998

llvm/docs/ReleaseNotes.rst

@@ -50,19 +50,6 @@ Non-comprehensive list of changes in this release
 
    Makes programs 10x faster by doing Special New Thing.
 
-Noteworthy optimizations
-------------------------
-
-* LLVM will now remove stores to constant memory (since this is a
-  contradiction) under the assumption the code in question must be dead.  This
-  has proven to be problematic for some C/C++ code bases which expect to be
-  able to cast away 'const'.  This is (and has always been) undefined
-  behavior, but up until now had not been actively utilized for optimization
-  purposes in this exact way.  For more information, please see:
-  `bug 42763 <https://bugs.llvm.org/show_bug.cgi?id=42763>_` and
-  `post commit discussion <http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20190422/646945.html>_`.  
-
-
 Changes to the LLVM IR
 ----------------------