`IRNormalizer`'s registry name `normalize` mismatches documentation

[mhjacobson]

commit 2e9f869 introduced a pass IRNormalizer, whose name in PassRegistry.def is normalize. However, the documentation was updated to state:

ir-normalizer: Transforms IR into a normal form that’s easier to diff

The docs should match the implementation.

[c-rhodes]

just hit this myself, posted a fix #141764