Fix mongoose docs generation

PUBLISHED_FROM=331821dcd1f7dc8a94581cd8a9b51aa00a89fddc

docs/c-api/intro.md

@@ -0,0 +1,16 @@
+---
+items:
+  - { name: mbuf.h }
+  - { name: mg_net.h }
+  - { name: mg_http.h }
+  - { name: mg_http_server.h }
+  - { name: mg_http_client.h }
+  - { name: mg_dns.h }
+  - { name: mg_dns_server.h }
+  - { name: mg_resolv.h }
+  - { name: mg_mqtt.h }
+  - { name: mg_mqtt_server.h }
+  - { name: mg_coap.h }
+  - { name: mg_util.h }
+  - { name: mg_uri.h }
+---