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_send_websocket_frame.md

@@ -0,0 +1,26 @@
+---
+title: "mg_send_websocket_frame()"
+decl_name: "mg_send_websocket_frame"
+symbol_kind: "func"
+signature: |
+  void mg_send_websocket_frame(struct mg_connection *nc, int op_and_flags,
+                               const void *data, size_t data_len);
+---
+
+Send websocket frame to the remote end.
+
+`op_and_flags` specifies frame's type, one of:
+
+- WEBSOCKET_OP_CONTINUE
+- WEBSOCKET_OP_TEXT
+- WEBSOCKET_OP_BINARY
+- WEBSOCKET_OP_CLOSE
+- WEBSOCKET_OP_PING
+- WEBSOCKET_OP_PONG
+
+Orred with one of the flags:
+
+- WEBSOCKET_DONT_FIN: Don't set the FIN flag on the frame to be sent.
+
+`data` and `data_len` contain frame data. 
+