[docs] Update ir-normalizer to normalize (#141764)

While the class name is IRNormalizer the registered name is "normalize"
and the docs should match this.

Fixes #136347.

Author: c-rhodes

llvm/docs/Passes.rst

@@ -554,8 +554,8 @@ variables with initializers are marked as internal.
 An interprocedural variant of :ref:`Sparse Conditional Constant Propagation
 <passes-sccp>`.
 
-``ir-normalizer``: Transforms IR into a normal form that's easier to diff
-----------------------------------------------------------------------------
+``normalize``: Transforms IR into a normal form that's easier to diff
+---------------------------------------------------------------------
 
 This pass aims to transform LLVM Modules into a normal form by reordering and
 renaming instructions while preserving the same semantics. The normalizer makes