Samples: net: civetweb: add README

Closes: #18212

Signed-off-by: Tomasz Gorochowik <tgorochowik@antmicro.com>

samples/net/sockets/civetweb/README.rst

@@ -0,0 +1,48 @@
+.. _sockets-civetweb-sample:
+
+Civetweb sample
+###############
+
+Overview
+********
+
+This sample application uses the HTTP APIs provided by the external `Civetweb <https://github.com/civetweb/civetweb>`_ module to create an HTTP server demonstrating selected Civetweb features.
+The Civetweb module is available as a west :ref:`module <modules>`.
+
+The source code for this sample application can be found at:
+:zephyr_file:`samples/net/sockets/civetweb`.
+
+Requirements
+************
+
+- A board with hardware networking
+- The Civetweb module (made available via west)
+
+Building and Running
+********************
+
+This sample was tested on the Atmel SAM E70 Xplained board, so this is the recommended target.
+
+Build it with:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/net/sockets/civetweb
+   :board: sam_e70_xplained
+   :goals: build
+   :compact:
+
+The sample application uses a static IP configuration.
+
+After flashing the board, the server can be accessed with the web browser of your choice at ``10.0.0.111:8080``.
+
+The sample does not serve any files like HTTP (it does not use any filesystem).
+Instead it serves the following three URLs:
+
+- ``/`` - a basic hello world handler
+- ``/info`` - shows OS information, uses the JSON format to achieve that
+- ``/history`` - demonstrates the usage of cookies
+
+A regular 404 status code is returned when trying to access any other URL.
+
+The IP configuration can be changed in Zephyr config.
+The default port can be changed in the sources of the sample.