Add nickserv config documentation

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

config.example.toml

@@ -105,3 +105,20 @@ module = "plugins.markov"
 # set. e.g. with a value of 0.01, a user may set their reply chance to 0.001.
 # default: 0.01
 # reply_chance = 0.01
+
+[[plugins]]
+module = "plugins.nickserv"
+
+# password
+# The password used to log in to this server using NickServ.
+password = "my_password"
+
+# email
+# The email address to use for this server when registering with NickServ.
+# default: omnibotomni.bot
+# email = "omnibotomni.bot"
+
+# nickserv
+# The nickname for the nickserv user.
+# default: "NickServ"
+# nickserv = "NickServ"