docs: Add services config guide and mention matching config<->register

docs/advanced-services-config.md

@@ -0,0 +1,67 @@
+# Advanced Service Config
+
+There are some service configuration options that you may want to be aware of.
+
+**NOTE**: Your SERVICE name in the `utils.registerService("SERVICE", desc=desc)`
+call and the service configuration in 'SERVICE::' **MUST** match for these
+directives to apply.
+
+
+#### Nick / Ident
+
+In addition to setting a per-server 'nick' or 'ident' using,
+
+```yaml
+servers:
+    somenet:
+        # ...
+        SERVICE_nick: OTHERNICK
+        SERVICE_ident: OTHERIDENT
+``` 
+
+You can also just set an arbitrary nick/ident using a per-**service** directive.
+
+```yaml
+SERVICE:
+    nick: OTHERNICK
+    ident: OTHERIDENT
+```
+
+#### JoinModes
+
+When joining a channel, ServiceBot Instances will just join and sit there.
+However, you can set a mode that the bot will ask for when it joins any channel.
+
+```yaml
+SERVICE:
+    joinmodes: 'o'
+```
+
+This would request the mode 'o' (usually op on most IRCds) when joining the channel.
+
+Technically any mode can be put here, but if an IRCd in question doesn't support
+the mode then it just ignores it.
+
+You can also use combinations of modes, such as 'ao' (usually admin/protect + op)
+
+```yaml
+SERVICE:
+    joinmodes: 'ao'
+```
+
+Combinations should work provided an IRCd in question supports it.
+
+#### Prefix
+
+You can also set the Service Bots fantasy prefix, of course this is only
+applicable if the 'fantasy' plugin is loaded.
+
+The setting allows for one or more characters to be set as the prefix.
+
+```yaml
+SERVICE:
+    prefix: './' 
+```
+
+This is perfectly valid, as is any other string.
+