[doc] GH Release may produce different TGZ files than what gets published on NPM

[zFernand0]

It's possible for npm packages to have variations between npmjs.org and what may get published to GH Releases using the following code snippet

octorelease/packages/npm/README.md

Lines 76 to 88 in b5d84d2

	```json
	{
	"plugins": [
	["@octorelease/npm", {
	"npmPublish": false,
	"tarballDir": "dist"
	}],
	["@octorelease/github", {
	"assets": "dist/*.tgz"
	}]
	]
	}
	```

I believe a warning might be good in order to remind developers that npm lifecycle hooks may not be executed when publishing with the GH plugin 😋