docs(env-and-mode): add override rule for the env

[poyoho]

Description

#6302

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[Shinigami92]

IMO it reads hard 🤔
Maybe better something like this? Could even be written better.

Suggested change

	Vite uses [dotenv](https://github.com/motdotla/dotenv) to load additional environment variables from the following files in your [environment directory](/config/#envdir) (if define the same variables will override variables in the following reverse order):
	Vite uses [dotenv](https://github.com/motdotla/dotenv) to load additional environment variables from the following files in your [environment directory](/config/#envdir) (if they define the same variable, the variable defined in the most specific file will win):

[poyoho]

I also think .env.${mode}.local is in the most specific, but it will be overwrite 😅

[poyoho]

in not the most specific will win?

[Shinigami92]

If the most specific currently don't win, then IMO this is a bug and should be changed
And I assume this is what #6306 is fixing 🤔

[userquin]

check https://cli.vuejs.org/guide/mode-and-env.html#environment-variables, see green alert with title Env Loading Priorities

[userquin]

this should be in sync with #6303 , I don't know if the last paragraph added is required, I don't know all vite internals (about restarting)...

[poyoho]

I test it. It need to restart.