[llvm] [Docs][CodeView] Document `S_LOCAL` and `S_DEFRANGE*` (PR #190156)

[Alexandre Ganea via llvm-commits]

================
@@ -184,27 +184,156 @@ S_ENVBLOCK (0x113d)
 S_LOCAL (0x113e)
 ^^^^^^^^^^^^^^^^
 
+Defines a local variable.
+This record is followed by a series of ``S_DEFRANGE*`` records that define the
+live range of this variable.
+
+All ``S_DEFRANGE*`` records consist of a header followed by
+``LocalVariableAddrRange`` and a list of ``LocalVariableAddrGap`` (until the
+record length is reached).
----------------
aganea wrote:

"...except for the ``S_DEFRANGE_FRAMEPOINTER_REL_FULL_SCOPE`` record."

https://github.com/llvm/llvm-project/pull/190156