Update networking layer w/ CURL and emscripten impl

External/curl-8.17.0/docs/cmdline-opts/user-agent.md

@@ -0,0 +1,29 @@
+---
+c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+SPDX-License-Identifier: curl
+Short: A
+Long: user-agent
+Arg: <name>
+Help: Send User-Agent <name> to server
+Protocols: HTTP
+Category: important http
+Added: 4.5.1
+Multi: single
+See-also:
+  - header
+  - proxy-header
+Example:
+  - -A "Agent 007" $URL
+---
+
+# `--user-agent`
+
+Specify the User-Agent string to send to the HTTP server. To encode blanks in
+the string, surround the string with single quote marks. This header can also
+be set with the --header or the --proxy-header options.
+
+If you give an empty argument to --user-agent (""), it removes the header
+completely from the request. If you prefer a blank header, you can set it to a
+single space (" ").
+
+By default, curl uses curl/VERSION, such as User-Agent: curl/`%VERSION`.