use/getting_started.rst: talk more about hostmasks

Adding strict hostmask isn't the only option, you can use wildcards and
the most used wildcards are now explained.

~~* nick starts with specific way (`nick*!ident@host`)~~
    ~~* server which has identd and bots with same ident~~
* any nick with specific ident (`*!ident@host`)
    * server which doesn't have bots, but has multiple users
* anything with specific host (`*!*@host`)
    * cloaks/vhosts