use "argument", "parameter" more consistently
use "argument", "parameter" more consistently

Be more consistent about using "argument" to mean a concrete value
provided by a function caller, and "parameter" to mean the abstract
input to the function.

Retain a few instances of the phrasing "in argument position",
because it appears in the RFCs and implementation. Also make a note
about the historical terminology inconsistency.

rust-lang/reference,rust-lang/reference