Refactor Mongoose documentation

PUBLISHED_FROM=e9a4e5c7b4a1d03b93a2a79e29de19e60e919929

docs/c-api/http_server.h/mg_send_response_line.md

@@ -0,0 +1,21 @@
+---
+title: "mg_send_response_line()"
+decl_name: "mg_send_response_line"
+symbol_kind: "func"
+signature: |
+  void mg_send_response_line(struct mg_connection *c, int status_code,
+                             const char *extra_headers);
+---
+
+Sends the response status line.
+If `extra_headers` is not NULL, then `extra_headers` are also sent
+after the reponse line. `extra_headers` must NOT end end with new line.
+Example:
+
+     mg_send_response_line(nc, 200, "Access-Control-Allow-Origin: *");
+
+Will result in:
+
+     HTTP/1.1 200 OK\r\n
+     Access-Control-Allow-Origin: *\r\n 
+