Request Configuration Docs are incorrect post v1

[Dru Sellers]

https://github.com/axios/axios-docs/blob/master/posts/en/req_config.md?plain=1#L56

Describe the bug

The documentation currently states that paramsSerialization is ...

paramsSerializer: function (params) {
    return Qs.stringify(params, {arrayFormat: 'brackets'})
},

However, after upgrading the correct configuration is ...

paramsSerializer: {
    encode: function(params) {
        return Qs.stringify(params, {arrayFormat: 'brackets'})
    }
},

[Shivam Kumar]

Please add hacktoberfest label to this issue