hooks-reference: bump to 2.0-alpha2
hooks-reference: bump to 2.0-alpha2

- Replace `IrcChannel`, `IrcUser`, and `IrcServer` with their new class names (`classes.Channel`, `classes.User`, and `classes.Server`)
- Replace `irc.fullVersion()` with `irc.version()`
- Various minor wording tweaks.

GLolol/PyLink