archive-emcpp: comments about possible cp cmd errors

bin/archive-emcpp.sh

@@ -1,7 +1,10 @@
 #!/bin/sh
 
 bin/build-emcpp.sh &&
-cp build/MyMoneroCoreCpp.js monero_utils/;
+cp build/MyMoneroCoreCpp.js monero_utils/; 
+# it's ok if certain combinations of the following error.
+# e.g. under wasm builds, you wouldn't want cp .wasm to be erroring.
+# under asmjs builds with .mem file enabled, you'd not want .mem to be erroring.
 cp build/MyMoneroCoreCpp.wasm monero_utils/;
 cp build/MyMoneroCoreCpp.wast monero_utils/;
 cp build/MyMoneroCoreCpp.js.mem monero_utils/