Refactor Mongoose documentation

PUBLISHED_FROM=e9a4e5c7b4a1d03b93a2a79e29de19e60e919929

docs/http/intro.md

@@ -0,0 +1,16 @@
+---
+title: HTTP
+items:
+  - { name: server_example.md }
+  - { name: client_example.md }
+  - { name: events.md }
+  - { name: files.md }
+  - { name: cgi.md }
+  - { name: ssi.md }
+  - { name: upload.md }
+  - { name: ssl.md }
+  - { name: digest_auth.md }
+  - { name: ../c-api/http.h/ }
+  - { name: ../c-api/http_server.h/ }
+  - { name: ../c-api/http_client.h/ }
+---