Fix output in curl command download for point annotations

[manasaV3]

In the curl command for point annotation download, we still say local.mrc the extension here should be the same as object being downloaded. For example, for annotations it should be local.ndjson.

[junxini]

extra context from Manasa: It doesn't prevent them from downloading the right thing, but if they use that command, it will save it locally with the wrong extension