merge doc to wiki

doc/hooks_chain.md

@@ -1 +0,0 @@
-packet, message handler chain???

doc/topic.md

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-Topic Types:
-
-static: 
-
-    /brokers/alerts/
-    /brokers/clients/connected
-    /brokers/clients/disconnected
-
-dynamic:
-    
-    created when subscribe...
-
-bridge:
-
-    cretated when bridge...
-
-
-## Create Topics
-
-emqttd_pubsub:create(Type, Name) 
-emqttd_pubsub:create(#topic{name = Name, node= node(), type = Type}).
-