Add DWARF string debug to clang release notes.

D12353 added inline strings to the DWARF info produced by clang. This
turns out to break some debugging software that assumes that a
DW_TAG_variable *must* come with a DW_AT_name. Add a release note to
broadcast this change.

Reviewed By: paulkirth

Differential Revision: https://reviews.llvm.org/D126224

Author: hctim

clang/docs/ReleaseNotes.rst

@@ -498,6 +498,13 @@ X86 Support in Clang
 DWARF Support in Clang
 ----------------------
 
+- clang now adds DWARF information for inline strings in C/C++ programs,
+  allowing ``line:column`` symbolization of strings. Some debugging programs may
+  require updating, as this takes advantage of DWARF ``DW_TAG_variable``
+  structures *without* a ``DW_AT_name`` field, which is valid DWARF, but may be
+  handled incorrectly by some software (e.g. new failures with incorrect
+  assertions).
+
 Arm and AArch64 Support in Clang
 --------------------------------