Remove old docs, rename docs_new to docs

It would be probably good idea to also remove tools/docgen.py and
asciidoc.mk, but asciidoc.mk is still mentioned under `cloud/doc`, which
may contain some useful info which we'll need at least to review before
removing.

PUBLISHED_FROM=faf454d4c52a2f07ea8ac084cf0bd11a0c9c9b3b

docs/c-api/http.h/mg_set_protocol_http_websocket.md

@@ -0,0 +1,50 @@
+---
+title: "mg_set_protocol_http_websocket()"
+decl_name: "mg_set_protocol_http_websocket"
+symbol_kind: "func"
+signature: |
+  void mg_set_protocol_http_websocket(struct mg_connection *nc);
+---
+
+Attach built-in HTTP event handler to the given connection.
+User-defined event handler will receive following extra events:
+
+- MG_EV_HTTP_REQUEST: HTTP request has arrived. Parsed HTTP request
+ is passed as
+  `struct http_message` through the handler's `void *ev_data` pointer.
+- MG_EV_HTTP_MULTIPART_REQUEST: A multipart POST request has received.
+  This event is sent before body is parsed. After this user
+  should expect a sequence of MG_EV_HTTP_PART_BEGIN/DATA/END requests.
+  This is also the last time when headers and other request fields are
+  accessible.
+- MG_EV_HTTP_REPLY: HTTP reply has arrived. Parsed HTTP reply is passed as
+  `struct http_message` through the handler's `void *ev_data` pointer.
+- MG_EV_HTTP_CHUNK: HTTP chunked-encoding chunk has arrived.
+  Parsed HTTP reply is passed as `struct http_message` through the
+  handler's `void *ev_data` pointer. `http_message::body` would contain
+  incomplete, reassembled HTTP body.
+  It will grow with every new chunk arrived, and
+  potentially can consume a lot of memory. An event handler may process
+  the body as chunks are coming, and signal Mongoose to delete processed
+  body by setting `MG_F_DELETE_CHUNK` in `mg_connection::flags`. When
+  the last zero chunk is received,
+  Mongoose sends `MG_EV_HTTP_REPLY` event with
+  full reassembled body (if handler did not signal to delete chunks) or
+  with empty body (if handler did signal to delete chunks).
+- MG_EV_WEBSOCKET_HANDSHAKE_REQUEST: server has received websocket handshake
+  request. `ev_data` contains parsed HTTP request.
+- MG_EV_WEBSOCKET_HANDSHAKE_DONE: server has completed Websocket handshake.
+  `ev_data` is `NULL`.
+- MG_EV_WEBSOCKET_FRAME: new websocket frame has arrived. `ev_data` is
+  `struct websocket_message *`
+- MG_EV_HTTP_PART_BEGIN: new part of multipart message is started,
+  extra parameters are passed in mg_http_multipart_part
+- MG_EV_HTTP_PART_DATA: new portion of data from multiparted message
+  no additional headers are available, only data and data size
+- MG_EV_HTTP_PART_END: final boundary received, analogue to maybe used to
+  find the end of packet
+  Note: Mongoose should be compiled with MG_ENABLE_HTTP_STREAMING_MULTIPART
+  to enable MG_EV_HTTP_MULTIPART_REQUEST, MG_EV_HTTP_REQUEST_END,
+  MG_EV_HTTP_REQUEST_CANCEL, MG_EV_HTTP_PART_BEGIN, MG_EV_HTTP_PART_DATA,
+  MG_EV_HTTP_PART_END constants 
+