Ignore npm5's package-lock.json (#3097)
Ignore npm5's package-lock.json (#3097)

As this project uses `yarn` to manage dependencies, `npm5`'s `package-lock.json` should be ignored.
This rule cannot be applied to global `.gitignore,` because in general it should be stored in git repository.
palantir/tslint,berickson1/tslint,berickson1/tslint,JoshuaKGoldberg/tslint,palantir/tslint,JoshuaKGoldberg/tslint,mprobst/tslint,andy-hanson/tslint,andy-ms/tslint,andy-ms/tslint,berickson1/tslint,mprobst/tslint,palantir/tslint,andy-ms/tslint,JoshuaKGoldberg/tslint,mprobst/tslint,andy-hanson/tslint,andy-hanson/tslint