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/mg_enable_multithreading.md

@@ -0,0 +1,14 @@
+---
+title: "mg_enable_multithreading()"
+decl_name: "mg_enable_multithreading"
+symbol_kind: "func"
+signature: |
+  void mg_enable_multithreading(struct mg_connection *nc);
+---
+
+Enable multi-threaded handling for the given listening connection `nc`.
+For each accepted connection, Mongoose will create a separate thread
+and run event handler in that thread. Thus, if an event hanler is doing
+a blocking call or some long computation, that will not slow down
+other connections. 
+