Refactor Mongoose documentation

PUBLISHED_FROM=e9a4e5c7b4a1d03b93a2a79e29de19e60e919929

docs/c-api/mqtt_server.h/intro.md

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+---
+title: "MQTT Server API reference"
+symbol_kind: "intro"
+decl_name: "mqtt_server.h"
+items:
+  - { name: mg_mqtt_broker_init.md }
+  - { name: mg_mqtt_broker.md }
+  - { name: mg_mqtt_next.md }
+  - { name: struct_mg_mqtt_session.md }
+  - { name: struct_mg_mqtt_broker.md }
+---
+
+
+

docs/c-api/mqtt_server.h/mg_mqtt_broker.md

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+---
+title: "mg_mqtt_broker()"
+decl_name: "mg_mqtt_broker"
+symbol_kind: "func"
+signature: |
+  void mg_mqtt_broker(struct mg_connection *brk, int ev, void *data);
+---
+
+Processes a MQTT broker message.
+
+The listening connection expects a pointer to an initialised
+`mg_mqtt_broker` structure in the `user_data` field.
+
+Basic usage:
+
+```c
+mg_mqtt_broker_init(&brk, NULL);
+
+if ((nc = mg_bind(&mgr, address, mg_mqtt_broker)) == NULL) {
+  // fail;
+}
+nc->user_data = &brk;
+```
+
+New incoming connections will receive a `mg_mqtt_session` structure
+in the connection `user_data`. The original `user_data` will be stored
+in the `user_data` field of the session structure. This allows the user
+handler to store user data before `mg_mqtt_broker` creates the session.
+
+Since only the MG_EV_ACCEPT message is processed by the listening socket,
+for most events the `user_data` will thus point to a `mg_mqtt_session`. 
+

docs/c-api/mqtt_server.h/mg_mqtt_broker_init.md

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+---
+title: "mg_mqtt_broker_init()"
+decl_name: "mg_mqtt_broker_init"
+symbol_kind: "func"
+signature: |
+  void mg_mqtt_broker_init(struct mg_mqtt_broker *brk, void *user_data);
+---
+
+Initialises a MQTT broker. 
+

docs/c-api/mqtt_server.h/mg_mqtt_next.md

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+---
+title: "mg_mqtt_next()"
+decl_name: "mg_mqtt_next"
+symbol_kind: "func"
+signature: |
+  struct mg_mqtt_session *mg_mqtt_next(struct mg_mqtt_broker *brk,
+                                       struct mg_mqtt_session *s);
+---
+
+Iterates over all MQTT session connections. Example:
+
+```c
+struct mg_mqtt_session *s;
+for (s = mg_mqtt_next(brk, NULL); s != NULL; s = mg_mqtt_next(brk, s)) {
+  // Do something
+}
+``` 
+

docs/c-api/mqtt_server.h/struct_mg_mqtt_broker.md

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+---
+title: "struct mg_mqtt_broker"
+decl_name: "struct mg_mqtt_broker"
+symbol_kind: "struct"
+signature: |
+  struct mg_mqtt_broker {
+    struct mg_mqtt_session *sessions; /* Session list */
+    void *user_data;                  /* User data */
+  };
+---
+
+MQTT broker. 
+

docs/c-api/mqtt_server.h/struct_mg_mqtt_session.md

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+---
+title: "struct mg_mqtt_session"
+decl_name: "struct mg_mqtt_session"
+symbol_kind: "struct"
+signature: |
+  struct mg_mqtt_session {
+    struct mg_mqtt_broker *brk;          /* Broker */
+    struct mg_mqtt_session *next, *prev; /* mg_mqtt_broker::sessions linkage */
+    struct mg_connection *nc;            /* Connection with the client */
+    size_t num_subscriptions;            /* Size of `subscriptions` array */
+    struct mg_mqtt_topic_expression *subscriptions;
+    void *user_data; /* User data */
+  };
+---
+
+MQTT session (Broker side). 
+