additional clarification on cfunction embedding (#52315)
Additional clarification to #45208 — in addition to some punctuation
tweaks, I added a sentence noting that using `@cfunction` to construct
and C function pointers, unlike `jl_call`, eliminates the overhead of
dynamic dispatch.
See also [this discourse
thread](https://discourse.julialang.org/t/jl-call-function-call-latency/106791).
