basic usage - promote safe version range
basic usage - promote safe version range

I'm aware this just an example, but it [leads readers to see it a best practise](https://github.com/Automattic/phpcs-neutron-standard/commit/40642df5ec9ea39871f1b99ada7fa34976169788#r29802440).

Having code with `"php": ">=5.4.0"` is pretty dangerous and will probably break with next major version.

```json
{
    "require": {
        "php": "^5.4"
    }
}
```

```json
{
    "require": {
        "php": "^7.1"
    }
}
```

is much more safer. Promoting best and proven practise should from *Basic usage* helps people to use composer the best way they can.

What do you think?
stof/composer,alcohol/composer,andrerom/composer,pierredup/composer,johnstevenson/composer,stefangr/composer,nicolas-grekas/composer,vdm-io/composer,floverdevel/composer,composer/composer,slbmeh/composer,fabpot/composer,milleruk/composer,naderman/composer,staabm/composer,localheinz/composer