This is exactly the reason that "Windows Subsystem for Linux" never made sense: the correct preposition would've been "including". Other suggestions: the verb phrase "consisting of"; the adverb "to wit" ("Windows Subsystem, to wit: Linux" has a nice ring to it); whatever part of speech "which is" is.
NB: This was added "later" that is why tons of projects were grandfathered in, because they were already called phpMyAdmin, phpMyFAQ, etc. (IIRC at least)
Now "Windows Subsystem for Linux" makes even less sense than it already did.