LangRef: Add !associated to list of preserved global metadata

[arsenm]

Accidental diff

[MaskRay]

LGTM.

[arsenm]

50b18d4140cf10c1bb5aeac6a89eab5d840853d5

llvm/docs/LangRef.rst

.. code-block:: llvm
     }
 
     @g1 = global i32 0, !dbg !22
     @g2 = external global i32, !dbg !22
 
 Unlike instructions, global objects (functions and global variables) may have
 multiple metadata attachments with the same identifier.
 
-A transformation is required to drop any metadata attachment that it does not
-know or know it can't preserve. Currently there is an exception for metadata
-attachment to globals for ``!func_sanitize``, ``!type`` and ``!absolute_symbol`` which can't be
+A transformation is required to drop any metadata attachment that it
+does not know or know it can't preserve. Currently there is an
+exception for metadata attachment to globals for ``!func_sanitize``,
+``!type``, ``!absolute_symbol`` and ``!associated`` which can't be
 unconditionally dropped unless the global is itself deleted.
 
 Metadata attached to a module using named metadata may not be dropped, with
 the exception of debug metadata (named metadata with the name ``!llvm.dbg.*``).
 
 More information about specific metadata nodes recognized by the
 optimizers and code generator is found below.