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/net.h/struct_mg_bind_opts.md

@@ -0,0 +1,22 @@
+---
+title: "struct mg_bind_opts"
+decl_name: "struct mg_bind_opts"
+symbol_kind: "struct"
+signature: |
+  struct mg_bind_opts {
+    void *user_data;           /* Initial value for connection's user_data */
+    unsigned int flags;        /* Extra connection flags */
+    const char **error_string; /* Placeholder for the error string */
+  #ifdef MG_ENABLE_SSL
+    /* SSL settings. */
+    const char *ssl_cert;    /* Server certificate to present to clients */
+    const char *ssl_ca_cert; /* Verify client certificates with this CA bundle */
+  #endif
+  };
+---
+
+Optional parameters to `mg_bind_opt()`.
+
+`flags` is an initial `struct mg_connection::flags` bitmask to set,
+see `MG_F_*` flags definitions. 
+