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/struct_http_message.md

@@ -0,0 +1,38 @@
+---
+title: "struct http_message"
+decl_name: "struct http_message"
+symbol_kind: "struct"
+signature: |
+  struct http_message {
+    struct mg_str message; /* Whole message: request line + headers + body */
+  
+    /* HTTP Request line (or HTTP response line) */
+    struct mg_str method; /* "GET" */
+    struct mg_str uri;    /* "/my_file.html" */
+    struct mg_str proto;  /* "HTTP/1.1" -- for both request and response */
+  
+    /* For responses, code and response status message are set */
+    int resp_code;
+    struct mg_str resp_status_msg;
+  
+    /*
+     * Query-string part of the URI. For example, for HTTP request
+     *    GET /foo/bar?param1=val1&param2=val2
+     *    |    uri    |     query_string     |
+     *
+     * Note that question mark character doesn't belong neither to the uri,
+     * nor to the query_string
+     */
+    struct mg_str query_string;
+  
+    /* Headers */
+    struct mg_str header_names[MG_MAX_HTTP_HEADERS];
+    struct mg_str header_values[MG_MAX_HTTP_HEADERS];
+  
+    /* Message body */
+    struct mg_str body; /* Zero-length for requests with no body */
+  };
+---
+
+HTTP message 
+