build: remove `.txt` files from .gitignore
Refs: https://github.com/nodejs/node/pull/32670#issuecomment-609498003
Checklist
-
make -j4 test(UNIX), orvcbuild test(Windows) passes -
commit message follows commit guidelines
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Refs: https://github.com/nodejs/node/pull/32670#issuecomment-609498003
make -j4 test (UNIX), or vcbuild test (Windows) passes