Clarify claims about PhantomData<T>.
Clarify claims about PhantomData<T>.

This wording was too strong.

Fixes #27523

graydon/rust,GBGamer/rust,pshc/rust,pshc/rust,l0kod/rust,dwillmer/rust,GBGamer/rust,l0kod/rust,l0kod/rust,zubron/rust,dwillmer/rust,pshc/rust,graydon/rust,pshc/rust,zubron/rust,pshc/rust,zubron/rust,jashank/rust,jashank/rust,pshc/rust,aidancully/rust,aidancully/rust,GBGamer/rust,graydon/rust,zubron/rust,GBGamer/rust,jashank/rust,l0kod/rust,dwillmer/rust,aidancully/rust,graydon/rust,aidancully/rust,zubron/rust,GBGamer/rust,dwillmer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,jashank/rust,zubron/rust,zubron/rust,pshc/rust,graydon/rust,zubron/rust,GBGamer/rust,dwillmer/rust,l0kod/rust,dwillmer/rust,dwillmer/rust,jashank/rust,dwillmer/rust,l0kod/rust,l0kod/rust,jashank/rust,jashank/rust,l0kod/rust,pshc/rust,aidancully/rust,jashank/rust,aidancully/rust