Welcome new users

## Welcome new users

When a new member joins the server, the bot should welcome them and provide some information about the server, this is currently done in [memberJoins.js](https://github.com/rich-howell/actual-bot/blob/master/events/guild/memberJoins.js) but can be modified to suit our requirements.

I don't think having random messages would work as we want the same message to be presented for everyone, or maybe we have the bot message them so only they can see the message and post a random welcome message for the community to see.

### Demo Server
https://discord.gg/5QMzbSBq

### ChannelID
Intro channel 1030544987957506068

### Message to the new member

```js
`Hello <@${member.id}>, welcome to The Actual Budget Discord server! You should be given access to the server after you verify that you have read the rules.

${member.guild.channels.cache.get('997025529494515733').toString()} if you have issues after verifying and refreshing your browser / restarting the app.

Say hi in ${member.guild.channels.cache.get('1030544987957506068').toString()} or dive right in. Look forward to talking to you.`
```

### Message to the community when member joins

Some random messages, encouraging the community to welcome the new member.

Start in events/guild/memberJoins.js, which the issue names as the current join-handler. Use the provided welcome text and channel IDs to update the new-member message, and decide from the issue text whether a separate community welcome is still needed. Done means a joining member receives the specified server information and the intro channel is referenced correctly.

索引モデルが issue の本文から書いたものです。