Docs are generated for Mongoose

Comments in headers are changed a bit: removed adoc-specific stuff,
markdown is used instead

PUBLISHED_FROM=9242cce85cc52a47a197d377e7e23804721a6bb5

docs/c-api/net.h/struct_mg_mgr.md

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+---
+title: "struct mg_mgr"
+decl_name: "struct mg_mgr"
+symbol_kind: "struct"
+signature: |
+  struct mg_mgr {
+    struct mg_connection *active_connections;
+    const char *hexdump_file; /* Debug hexdump file path */
+  #ifndef MG_DISABLE_SOCKETPAIR
+    sock_t ctl[2]; /* Socketpair for mg_wakeup() */
+  #endif
+    void *user_data; /* User data */
+    void *mgr_data;  /* Implementation-specific event manager's data. */
+  #ifdef MG_ENABLE_JAVASCRIPT
+    struct v7 *v7;
+  #endif
+  };
+---
+
+Mongoose event manager. 
+