Update loo2-moment-matching.Rmd

[ci skip]

vignettes/loo2-moment-matching.Rmd

@@ -163,10 +163,9 @@ __rstan__. It only requires setting the argument `moment_match` to `TRUE` in the
 `loo()` function. Optionally, you can also set the argument `k_threshold` which
 determines the Pareto $k$ threshold, above which moment matching is used. By
 default, it operates on all observations whose Pareto $k$ value is larger than
-0.7. (NOTE: Using moment matching directly using the `loo()` function is
-currently available in the development version of __rstan__ in
-https://github.com/topipa/rstan, but will be available in the CRAN release
-eventually).
+0.7. (NOTE: using moment matching directly via the `loo()` function will be
+available in __rstan__ > 2.19.3. Until then use
+https://github.com/stan-dev/rstan/pull/743.)
 
 ```
 loo2 <- loo(fit, moment_match = TRUE)