net: doc: Remove Network Connectivity API page

The Network Connectivity API page is kind of pointless, as it provides
little information (which can be found elsewhere as well) and it was
pointer out that it kind of creates noise in the documentation as it can
be confused with the page which provides a summary of network APIs.

Therefore, remove the page, and move the information from it elsewhere.
The brief summary of what APIs to use was moved the Networking APIs
index page. The information about the samples demonstrating BSD sockets
API usage was moved to the BSD sockets documentation page itself.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>

doc/_scripts/redirects.py

@@ -16,6 +16,7 @@
     ('application/index', 'develop/application/index'),
     ('boards/x86/ehl_crb/doc/index', 'boards/x86/intel_ehl/doc/index'),
     ('boards/x86/rpl_crb/doc/index', 'boards/x86/intel_rpl/doc/index'),
+    ('connectivity/networking/networking-api-usage', 'connectivity/networking/api/index'),
     ('development_process/code_flow', 'project/code_flow'),
     ('development_process/index', 'project/index'),
     ('development_process/issues', 'project/issues'),

doc/connectivity/networking/api/index.rst

@@ -3,6 +3,17 @@
 Networking APIs
 ###############
 
+Zephyr provides support for the standard BSD socket APIs (defined in
+:zephyr_file:`include/zephyr/net/socket.h`) for the applications to
+use. See :ref:`BSD socket API <bsd_sockets_interface>` for more details.
+
+Apart of the standard API, Zephyr provides a set of custom networking APIs and
+libraries for the application to use. See the list below for details.
+
+.. note::
+   The legacy connectivity API in :zephyr_file:`include/zephyr/net/net_context.h`
+   should not be used by applications.
+
 .. toctree::
    :maxdepth: 2
 

doc/connectivity/networking/api/sockets.rst

@@ -57,6 +57,10 @@ there is a table mapping file descriptors to internal object pointers.
 The file descriptor table is used by the BSD Sockets API even if the rest
 of the POSIX subsystem (filesystem, stdin/stdout) is not enabled.
 
+See :zephyr:code-sample:`sockets-echo-server` and :zephyr:code-sample:`sockets-echo-client`
+sample applications to learn how to create a simple server or client BSD socket based
+application.
+
 .. _secure_sockets_interface:
 
 Secure Sockets

doc/connectivity/networking/index.rst

@@ -12,7 +12,6 @@ operation of the stacks and how they were implemented.
 
    overview.rst
    net-stack-architecture.rst
-   networking-api-usage.rst
    networking_with_host.rst
    network_monitoring.rst
    api/index.rst