add more files and folders to `.npmignore`

[marrws]

Reproduction steps

Download tarball from this url:

$ npm view graphql-subscriptions dist.tarball

List content of the file

$ tar -tf graphql-subscriptions-3.0.0.tgz 
package/AUTHORS
package/CHANGELOG.md
package/.circleci/config.yml
package/CODEOWNERS
package/CONTRIBUTING.md
package/.designs/authorization.md
package/dist/index.d.ts
package/dist/index.js
package/dist/index.js.map
package/dist/pubsub-async-iterable-iterator.d.ts
package/dist/pubsub-async-iterable-iterator.js
package/dist/pubsub-async-iterable-iterator.js.map
package/dist/pubsub.d.ts
package/dist/pubsub-engine.d.ts
package/dist/pubsub-engine.js
package/dist/pubsub-engine.js.map
package/dist/pubsub.js
package/dist/pubsub.js.map
package/dist/with-filter.d.ts
package/dist/with-filter.js
package/dist/with-filter.js.map
package/.github/ISSUE_TEMPLATE.md
package/.github/PULL_REQUEST_TEMPLATE.md
package/LICENSE
package/package.json
package/README.md
package/.travis.yml

Expected result

• Folders and files not needed for the package to work should be ignored when publishing the package.

Actual result

• Unneeded files are included in the tarball like .github/, .circleci/, .designs/, .travis.yml and more